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psychology of addiction > Cell Bio Exam 3 > Flashcards

Cell Bio Exam 3 Flashcards

1
Q

What are the 2 main parts of the vesicular transport?

A

Vesicle budding and fusion

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2
Q

Default Pathway Route

A

Goes from RER to Golgi to plasma membrane (PM)

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3
Q

2 signals required to divert from the default pathway

A
  1. Retention signals
  2. diversion signals
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4
Q

Function of Golgi Apparatus

A

Plays critical role in biosynthesis, sorting, dispatching, and recycling of proteins to various parts of the cell

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5
Q

Structure of the Golgi apparatus

A

From entrance to exit:
1. cis golgi network
2. cis cisterna
3. medial cisterna
4. trans cisterna
5. trans golgi network

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6
Q

Function of the perinuclear (aka golgi apparatus)

A

To remove and add sugars to glycoproteins through the action of resident glycosidases and glycotransferases

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7
Q

What molecules in the golgi add on sugars

A

glycosyltransferases

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8
Q

What molecules in the golgi cleave sugars?

A

glycosidases

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9
Q

What 2 parts of the golgi apparatus make up the “sorting reticulum”

A
  1. cis golgi network
  2. trans-golgi network
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10
Q

Purpose of cis-golgi network

A

passes proteins to the cis-golgi stack or returns them to the ER
- basically sorts what comes into the golgi

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11
Q

Purpose of trans-golgi network

A

passes proteins to the plasma membrane, lysosomes, or secretory vesicles
- sorts where proteins go after exiting the golgi

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12
Q

purpose of the medial golgi

A

this is where the glycosidase and glycosyltransferase reactions occur

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13
Q

Purpose of the intra-golgi

A

Transport vesicles

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14
Q

What is the rate-limiting step in protein transport and secretion?

A

Export from the ER

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15
Q

Questions that ER machinery asks

A

Is the protein correctly folded and assembled with other subunits

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16
Q

If ER detects that proteins are not correctly folded what occurs?

A

The denatured or unfolded protein is degraded

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17
Q

What occurs if the ER detects that the protein is not correctly assembled with other subunits?

A

If protein is still attached to BiP or other chaperones, and is actively still undergoing folding, then proteins remains in the ER

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18
Q

What is BiP

A

BiP is a heat shock protein (part of HSP70 family) found in the ER that helps protein with folding

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19
Q

What occurs if the ER detects that the protein is correctly folded and assembled with other subunits?

A

The protein will be exported by the default pathway to the cis-Golgi network

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20
Q

What occurs to misfolded p in the ER lumen?

A

A misfolded p will be moved out back through the Sec61 complex where it will bind to a N-glycanase. This will lead to ubiquitin binding to it and the p will be degraded by a proteosome

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21
Q

2 ER Retention Signals

A
  1. BiP
  2. PDI
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22
Q

What is the sequence for ER retention signals?

A

KDEL, short AA sequence

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23
Q

What binds to KDEL sequence

A

KDEL receptors present in ER and cis-Gogli

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24
Q

KDEL Recycling Steps

A
  1. Secretory proteins and ER resident protein receptors are moved along the default pathway from the ER to the golgi. ER resident p are also sent to golgi in separate vesicles
  2. ER resident p containing KDEL sequence bind to the ER p receptors in the golgi and are then recycled back to ER
  3. return requires use of Microtubules
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25
Q

Name for KDEL Retrieval Mechanism

A

Retrograde Transport

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26
Q

KKXX Sequence

A

sequence that is present in some membrane p that can be recycled back to ER

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27
Q

What happens if the KDEL Sequence is mutated

A

Protein will go to the cell surface and not be recycled back to ER

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28
Q

Proteins in Rough ER are either….

A
  1. resident
  2. en route to other destinations
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29
Q

What requirements must proteins meet before they can leave the RER?

A
  1. folded
  2. modified
  3. assembled correctly for proper function
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30
Q

3 molecule types that ensure that a protein is ready to leave the ER

A
  1. Chaperones
  2. Isomerases
  3. Glycosyltransferases/glycosidases
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31
Q

ER Chaperones

A

BiP (HSP 70 family member)
calnexin
calreticulin

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32
Q

Monoglucosylated glycoproteins

A

Calnexin and calreticulin are Ca dependent and help with p folding

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33
Q

Function of ER Chaperones

A
  • Prevent aggregation of hydrophobic domains
    and facilitate folding in ATP-dependent manner
  • help retain partially folded p in ER avoiding premature transit to golgi
  • also facilitate translocation (similar to mt-hsp7- activity)
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34
Q

Function of isomerases

A

ex: protein disulfide isomerase (PDI)
Help form disulfide bonds to prevent p from going to golgi

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35
Q

Function of glycosyltransferases and glycosidases

A

Glycosyltransferases (adding sugars)
Glycosidases (cleave sugars)

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36
Q

Glycosylation Function

A

P in ER lumen are post-translationally glycosylated

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37
Q

How are Oligosaccharide Precursors Formed?

A

Oligosaccharides assembled from nucleotide and lipid phosphate monosaccharides in the cytosol and ER through a sequential series of transfer reactions. Precursor is first assembled on lipid carrier called dolichol

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38
Q

Steps of Synthesis of Oligosaccharide Precursor

A

On cytosol side
1. phosphorylation of dolichol by ATP hydrolysis
2. 2 nucleotide UDP-GlcNAc are added to the dolichol
3. 5 GDP-Man are added to doichol complex
4. Flipping occurs in membrane
On lumen side
5. 4 dolichol phosphate Man are added to the dolichol complex
6. 3 dolichol phosphate Glc are added to dolichol complex

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39
Q

What occurs after oligosaccharide precursor is assembled?

A

oligosaccharide is transferred to the Asn residue of a protein in the ER lumen

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40
Q

What catalyzes the transfer of oligosaccharide precursor to a protein?

A

Oligosaccharyl transferase

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41
Q

What complex is associated with oligosaccharyl transferase that help speed up p modifications after translocation to lumen?

A

Sec61 complex

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42
Q

What is removed from the high mannose glycan complex before it exits the ER?

A

terminal 3-Glc and 1-Man are removed before the complex exits ER

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43
Q

What occurs to the glycan complex once it reaches the golgi?

A

Further removal/addition of sugars using:
- glycosidases (remove)
- glycosyltransferases (add)

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44
Q

What are the 2 types of attachment bw oligosaccharide and Asn

A

N-linked or O-linked

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45
Q

What is the consensus glycosylation sequence

A

A-X-Ser/Thr
X can be any AA except Proline

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46
Q

What are the 2 types of oligosaccharides studied in class

A
  1. Complex oligosaccharides
  2. high mannose oligosaccharides
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47
Q

What are the 3 destinations that particles are sent to after sugar processing occurs in the golgi

A
  • lysosome
  • PM
  • secretory vesicle
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48
Q

What are the 2 golgi structure models

A
  1. vesicular transport model
  2. cisternal maturation model
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49
Q

What is the vesicular transport model

A

Model that explains that golgi is static and transport vesicles ferry cargo between stacks

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50
Q

What is the cisternal maturation model

A

Model that explains that as Golgi cisternae mature, they move forward through stack
- at each stage, Golgi resident proteins carried forward are moved backward via vesicular transport

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51
Q

What is endocytosis

A

vesicular import of particulates and macromolecules

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52
Q

What is stored in lysosomes

A

acid hydrolases that are used for degradation

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53
Q

What hydrolases are found in lysosomes

A

nucleases, proteases, glycosidases, lipases, phosphatases, sulfatases, phospholipases

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54
Q

What is required to keep the low pH in lysosomes

A

The H+ pump which is a V-type ATPase that acidifies lysosome environment

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55
Q

What are the 4 pathways used to deliver material to the lysosome

A
  • biosynthetic pathway from ER-golgi
  • endocytic pathway from outside environment and brought into cell by endocytosis
  • autophagic pathway (self destruct)
  • phagocytic pathway (endocytosis in specialized cells like macrophages and neutrophils)
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56
Q

what synthesizes and sorts lysosomal hydrolases and membrane proteins

A

Golgi

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57
Q

How are lysosomal hydrolases and membrane proteins delivered to lysosome

A

delivered via transport vesicles that traffic through late endosomes

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58
Q

What are the 2 ways lysosomal proteins are specifically selected for delivery to late endosomes/lysosomes relative to other pathways?

A

lysosome hydrolases have 2 types of molecular signals
- signal patch
- M6P marker

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59
Q

How does a signal patch ensure that hydrolases are delivered to lysosome

A

A signal patch is read by glycosyltransferases in cis-Golgi that add an M6P tag to proenzymes

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60
Q

How does a M6P tag ensure that hydrolases are sent to lysosome

A

M6P is read by M6P receptors present in the trans-Golgi network then M6P bind and segregate hydrolases from the other protein traffic exiting the Golgi

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61
Q

Steps of hydrolase traveling to lysosome

A
  1. lysosomal hydrolase precursor from ER has M6P tag added in cis-golgi network
  2. precursor then travels to trans network where M6P receptors recognize the tag and bind
  3. Clathrin-coated transport vesicle is created and travels to late endosome (receptor dependent transport)
  4. Vesicle fuses with late endosome where H+ pump triggers the release of M6P tag
  5. M6P receptor is dissociated from precursor due to acidic pH of late endosome
  6. M6P receptor budding vesicle is created and recycled back to trans-golgi network
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62
Q

What are LAMPs

A

lysosome associated membrane proteins that follow the default secretory pathway to the plasma membrane

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63
Q

What is another name for lysosome membrane protein pathway

A

scavenger pathway

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64
Q

What path do the majority of lysosome direct proteins take to arrive at lysosome?

A

ER to golgi to late endosome to lysosome

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65
Q

What is the alternative pathways for proteins to arrive at lysosome

A

Lysosome membrane protein pathway

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66
Q

What path do proteins take in scavenger pathway

A

ER to golgi to PM to early endosome to late endosome to lysosome

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67
Q

Pathway to PM in scavenger pathways is also followed by?

A

small percent of hydrolases and M6P receptors

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68
Q

What are 2 lysosomal storage diseases that occur due to mutations

A
  1. hurler’s disease
  2. I-Cell disease
    I stands for inclusion
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69
Q

What is mutated in Hurler’s disease

A

Lysosomal ez required for breakdown of glycosaminoglycans (ECM proteins) is missing

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70
Q

What is mutated in I-cell disease?

A

Defect in GlcNAc phosphotransferase causing there to be no M6P tag

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71
Q

What is the effect of no M6P tag in I-Cell disease?

A

M6P receptors fail to sort and target hydrolases

72
Q

Function of endocytosis

A
  • uptake of nutrient molecules
  • clearance of harmful substances, cell debris and infectious organisms
  • maintenance of surface-to-volume ratio
73
Q

3 types of endocytosis

A
  1. phagocytosis
  2. receptor mediated endocytosis
  3. pinocytosis
74
Q

What occurs to majority of ingested material during endocytosis?

A

material is delivered to lysosomes for degradation

75
Q

Phagocytosis function

A
  • cell eating
  • uptake of large particulate matter
  • engulfs material
76
Q

Receptor mediated endocytosis function

A

uptake of macromolecules via specific cell surface receptors
- ligands are smaller in size

77
Q

Pinocytosis function

A
  • “cellular sipping/drinking”
  • uptake of fluid and dissolved solutes
  • uptake of bulk volume
78
Q

2 main features of phagocytosis

A
  1. practiced by a select group of cells
  2. receptor-mediated event
79
Q

In what cells does phagocytosis occur?

A
  • protozoa (giant amoebae) ingest food particles
  • macrophages and neutrophils (binding, clearance, and destruction of bacteria, damaged cells, and cellular debris)
  • fibroblasts (remodeling of connective tissues)
80
Q

How is phagocytosis a receptor-mediated event

A
  • cells possess surface receptors that recognize specific or generic sites on various particles
  • cells bind particle then progressively extend pseudopodia to engulf particles
  • engulfment requires receptor-ligand interactions around surface of particle
81
Q

How does the pseudopodia extend?

A
  1. receptor ligand interactions induce localized changes in cortical cytoplasm
    - Ca2+ influx induce formation of gel like cytoplasm
    - membrane coupled pseudopod extension and actin polymerization
  2. engulfment completed when pseudopodia meet and fuse forming phagosome
82
Q

2 ways that ingested particles are degraded?

A
  1. oxygen metabolites help kill bacteria for particles that reside in phagosomes
  2. the acid hydrolases digest contents in phagolysosomes
83
Q

What are phagolysosomes

A

product of fusion of lysosomes with phagosomes

84
Q

What are residual bodies

A

phagolysosomes containing non-digestible material

85
Q

3 ways that pathogens use to avoid phagocytosis degradation

A
  1. escape
    - break phagocytic walls
  2. prevent fusion w/ lysosomes
    - don’t bind with lysosome
  3. survive in phagolysosome
    - survive in harsh environment w/ thick layer of pathogens
86
Q

Example of escape phagocytosis mechanism

A

listeria virulence

87
Q

Steps in Listeria virulence

A
  1. listeria attaches to E-cadherin
  2. uptake by zipper mechanism
  3. hemolysin secretion
  4. hemolysin mediated membrane disruption
  5. bacterial release and replication
  6. hemolysin destroyed in host proteosome
  7. released bacteria will grow tail using actin nucleation
  8. bacteria moves w/ actin tail to PM
  9. Protrusion formation occurs before bacteria is engulfed by neighboring host cell
88
Q

2 mechanisms to attach bacterium to host cell

A
  1. zipper mechanism
  2. trigger mechanism
89
Q

Zipper mechanism steps

A
  1. The adhesin on bacteria will bind to adhesin receptors on host cells
  2. leads to actin filament increasing and absorbing bacterium
90
Q

2 examples of adhesin receptors

A

integrins and cadherins

91
Q

Trigger mechanism steps

A
  1. type 3 secretion apparatus on bacterium binds to the host cell
  2. activates the Rho-family GTPase
  3. activation triggers actin polymerization
  4. actin polymerization then absorb bacterium
92
Q

Pathogen that uses integrin adhesin receptor

A

Yersinia uses invasin-beta1 integrin

93
Q

Pathogen that uses e-cadherin adhesin receptor

94
Q

2 main features of Receptor mediated endocytosis

A
  1. vesicular uptake of macromolecules
  2. uptake mediated by specific cell surface receptors that increase efficiency of uptake
95
Q

Macromolecules in RME

A
  1. Nutrients
    • Lipoproteins : LDL and HDL
    • metals: Fe
  2. Hormones
  3. growth factors
  4. immunoglobulins
  5. harmful substances
    • modified glycoconjugates or coagulation
      factors
96
Q

Cholesterol in RME

A

Cholesterol is take up via LDL receptors and delivered to lysosomes

97
Q

Why are some people predisposed to heart attacks

A

Genetic analysis shows defective LDL receptors that result in increase in blood serum cholesterol levels

98
Q

Why do specific cell surface receptors lead to an increase in efficiency?

A
  • bind ligands with high affinity
  • receptor ligand complexes enter cells specialized membrane structures aka clathrin coated pits
99
Q

What are clathrin-coated pits?

A

Specialized endocytic structures that collect endocytic receptors

100
Q

2 results of clathrin coated pits

A
  1. exclude other membrane proteins
  2. concentrate endocytic receptors
101
Q

What 2 effects would occur if clathrin adaptor proteins were defective?

A
  1. reduced binding to cargo (LDL)
  2. defective cytoplasmic tails
102
Q

what are the 2 proteins involved in coated pits?

A
  1. clathrin
  2. adaptor complexes (proteins)
103
Q

Structure of clathrin

A

3 heavy chains and 3 light chains which form a heterohexamer

104
Q

what is the building block for clathrin

A

a triskelia/triskelion

105
Q

what does the structure of a clathrin coat look like

A

when clathrin triskelion self assemble they form a lattice composed of hexagons and pentagons like a soccer ball

106
Q

Function of clathrin adaptors

A

complexes that mediate clathrin binding to specific membrane receptors

107
Q

types of clathrin adaptors

A
  1. plasma membrane AP-2
  2. trans-golgi network AP-1
108
Q

What is the purpose of endocytosis signal motifs?

A

the endocytic receptors possess 4 AA motif that mediate interaction with coated pit proteins

109
Q

What is the key feature of an endocytosis signal motif

A

Protruding loop with aromatic amino acid, often Tyr

110
Q

2 examples of endocytosis signal motifs sequences

A
  1. NPXY (LDL receptor)
  2. FRXY (transferrin receptor)
111
Q

Clathrin Cycle steps

A
  1. Adaptor proteins are recruited to PM
  2. Triskelia bind to adaptor complex
  3. Triskelia reorganize into soccer ball
  4. the stalk of pit invagination is pinched off using dynamin
  5. Clathrin uncoating mediated by clathrin associated hsp ATPase
112
Q

What are the main 3 endosomal compartments

A
  1. early endosome
  2. late endosome
  3. lysosome
113
Q

What is the function of the early endosome

A

sorting and recycling center

114
Q

What is the function of the late endosome?

A

depository for ligands targeted for degradation

115
Q

What is the function of lysosome?

A

House acid hydrolases and fuse with late endosomes to then be able to degrade proteins

116
Q

What is the pH of the different endosomal compartments?

A
  1. early endosome
    • pH = 6-6.5
  2. late endosome
    - pH = 5.5-6.0
  3. Lysosome
    - pH = <5.5
117
Q

RME Pathway for LDL

A
  1. endocytosis
  2. uncoating
  3. fusion with endosome
  4. LDL trafficked to lysosome
  5. LDL degraded in lysosome and release of free cholesterol
  6. LDL receptor is recycled back to PM
118
Q

What triggers the release of glucose receptors to PM

A

Insulin binding to insulin receptor triggers release of glu receptors to PM to boost glu uptake into the cell

119
Q

Retrieval Pathway

A

When protein receptors are recycled back to the golgi complex
- ex: M6P receptor back to trans-golgi

120
Q

Biosynthetic Pathway

A

LAMPs and M6P receptor positive
- when particle travels along default pathway up the PM and is then endocytosed (early to late to lysosome)

121
Q

Endocytic Pathway

A

LAMP positive and M6P receptor negative
- when external components are endocytosed (PM to early to late to lysosome)

122
Q

Types of Neiman Pick Diseases

A

Type A, B, and C

123
Q

What deficiency occurs in Neiman Pick Type A and B diseases?

A

Ez deficiency of acid sphingomyelinase (ASM) which is ez that breaks down sphingolipids. This causes a buildup of sphingolipids in the cell causing the cell to die and damage organs

124
Q

Features of Type A Nieman Pick Disease

A

Associated with neurological tissues and usually causes death within 2-3 years

125
Q

Symptoms of Type B Neiman Pick Disease

A

Enlarged spleen, respiratory problems, cardiovascular problems, can live into adulthood

126
Q

What mutation occurs in Type C Neiman Pick Disease?

A

Mutation in NPC1 protein which is needed for cholesterol transport. Leads to accumulation of cholesterol in late endosome and it cannot be released. Causes block of retrograde transport of M6P receptors to the golgi transport

127
Q

Steps that lead to degradation of receptors?

A
  1. receptors tagged with ubiquitin are endocytosed to early lysosome
  2. Ubiquitin is recognized by ECRT protein complexes (1, 2, 3) leading to invagination of receptor into the late endosome
  3. Multivesicular body combines with transport vesicle that contains lysosomal proteases and lipases.
  4. Receptors w/ ubiquitin tags are degraded by proteases and lipases in the lysosome
128
Q

Example of when receptor needs to be degraded

A

Growth factor

129
Q

How do some MVBs undergo exocytosis

A

Limiting membrane of MVB fuse with PM and ILV are released converting them to exosomes

130
Q

Steps in transcytosis

A
  1. Antibody binds to Fc receptor on the apical membrane and is endocytosed
  2. Goes to early endosome then moves to recycling endosome
  3. Receptor and antibody are then transcytosed to the basal membrane
  4. Recycling vesicle with PM returns to apical membrane
131
Q

In what cells does transcytosis occur?

A

In polarized cells such as epithelial cells (intestine or bloodstream)

132
Q

What are the 5 possible fates for Receptors and Ligands?

A
  1. receptor recycled and ligand degraded
  2. receptor and ligand recycled
  3. receptor and ligand are degraded
  4. Receptor and ligand move from one membrane domain to another (transcytosis)
  5. Receptor recycled and ligand stored
133
Q

Example of when receptor is recycled and ligand is degraded

A

LDL receptor and LDL particles

134
Q

Example of when both receptor and ligand are recycled

A

Apotransferrin and Transferring receptor

135
Q

Example of when receptor and ligand are degraded

A

Epidermal Growth factor, EGF receptor

136
Q

Example of when receptor and ligand are moved from one membrane domain to another

A

maternal IgGs, when a baby receives antibodies during lactation

137
Q

Example of when receptor is recycled and ligand is stored

A

vitelligenin in oocytes

138
Q

What is pinocytosis

A

uptake of fluid, nonspecific volume taken up in bulk

139
Q

Where does pinocytosis occur

A

in all eukaryotic cells

140
Q

2 pathways of pinocytosis

A

clathrin dependent and independent pathways

141
Q

Functions of pinocytosis

A
  1. non-specific uptake of solutes
  2. routine turnover of PM proteins and lipids
  3. maintenance of surface-to-volume ratio
142
Q

what are caveolae?

A

non-clathrin coated membrane structures

143
Q

main protein in caveolae?

144
Q

Potential functions of caveolae

A
  1. pinocytosis (clathrin independent)
  2. uptake of small solutes
  3. site of cell signaling
145
Q

what is exocytosis?

A

vesicular export of molecules out of the cell

146
Q

General features of exocytosis

A
  • membrane p and lipids delivered to provide new components to PM while soluble cargo can be secreted to extracellular space
  • 2 main pathways
147
Q

2 pathways of exocytosis

A
  1. constitutive transport
  2. regulated secretion
148
Q

function of exocytosis

A

maintain balance of inward membrane flow with outward membrane flow

149
Q

Purpose of constitutive transport

A
  • transports secretory vesicles from the TGN to the PM
  • delivers proteoglycans and glycoproteins out of cell
150
Q

Purpose of Regulated secretion

A
  • special class of secretory vesicles that rely on rapid, signal dependent release
151
Q

What is regulated pathway dependent on

A

assembly of vesicle is clathrin dependent, microtubule and actin cytoskeleton dependent, and release of cargo is signal dependent

152
Q

Essential features of constitutive secretion

A
  • flow is continuous, does not require signal
  • supplies PM with new lipids and proteins
  • movement is clathrin independent
  • cargo is not concentrated
153
Q

Examples of constitutive secretion

A

serum albumin, transferrin in mammalian hepatocytes

154
Q

What cell types follow regulated secretion

A
  • neurons, Beta islet cells, mast cells, goblet cells, sperm, eggs
  • neurotransmitters, insulin, histamine, mucins
155
Q

How does TGN specifically sort and concentrate molecules for regulated secretion

A

Use a sorting signal thought to be some type of patch that lead to distinct secretory vesicles (or granules)

156
Q

Are regulated secreted vesicles clathrin dependent

A

yes, they use a clathrin mediated mechanism to bud vesicle
- involves acidification by V-type ATPase

157
Q

What is used to move vesicles in regulated secretion pathway?

A

Kinesin (microtubules) and myosin 1 (actin) needed for movement and actin rearrangement helps with exocytosis release

158
Q

what adaptor protein is used in vesicle budding in regulated secretion

A

Requires AP-1 for clathrin mediated budding of golgi derived vesicles

159
Q

What occurs after budding to the secretory vesicle in exocytosis

A

immature secretory vesicles are uncoated and undergo further maturation which help to condense vesicle contents

160
Q

How are proteins packaged during exocytosis when in immature secretory vesicles?

A

they are packaged in a precursor form and are further process prior or just after secretion
- ex: polypeptide hormones, neuropeptides, and hydrolytic enzymes

161
Q

Examples of precursor proteins stored in immature secretory vesicles

A
  • proinsulin to insulin
  • digestive enzymes
162
Q

what is the advantage of storing proteins in precursor form

A

cells will release cargo only when needed and signal is sent

163
Q

What 2 changes occur as vesicle is matured in exocytosis

A
  1. cargo concentration increases
  2. cargo is acidified w/ V-type
164
Q

how are vesicles apposed to the PM

A

enmeshed in the cortical actin-membrane cytoskeleton network

165
Q

What is required for release of cargo once it is at the PM

A

A signaling event is required and trigger secretory granules to fuse with PM and release cargo to extracellular space

166
Q

What intracellular signal occurs when specific ligands bind receptors on cell surface

A

Influx of Ca levels

167
Q

Increase in intracellular Ca levels leads to

A
  • transient disruption or fragmentation of cortical cytoskeletal network
  • vectorial movement of vesicle to the PM where membrane fusion and secretion occur
168
Q

Steps leading to exocytosis

A
  1. vesicle arrives with help of microtubule and docks on cortex
  2. ligand binds receptor which trigger rise in Ca levels, disruption in actin network, and vesicle interaction with PM
  3. vesicle membrane fuses with PM releasing content of vesicle
169
Q

When does mast cell degranulation occur

A

when cell is introduced to allergen that the body detects as an invader and results in granules releasing histamine

170
Q

Can regulated exocytosis be localized

A

yes, an exp demonstrated that when histamine is released at localized cite, after mast cell exposure to stimulant coupled to a bead, exocytosis only occurred at site of contact with bead

171
Q

What does allergy medication do

A

Allergy medicine is an antihistamine that blocks released histamine to prevent histamine from triggering allergy symptoms such as inflammation and increase in body temp

172
Q

what does protein efflux from TGN require

A

both signal mediated diversion to lysosomes and signal mediated diversion to secretory vesicles require clathrin coating

173
Q

What are the 2 routes of protein sorting from TGN in polarized cells

A
  1. direct pathway
  2. indirect pathway
174
Q

what is the direct pathway for protein sorting from TGN in polarized cells

A

from TGN to correct PM domain (apical or basal)

175
Q

What is the indirect protein sorting pathway from TGN in polarized cells

A

From TGN to incorrect domain
- protein then transported to correct domain via transcytosis
- ex: protein that are meant for basal membrane are sent to apical membrane by accident and are then transcytosed to basal membrane

psychology of addiction (3 decks)

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