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Mbb231 > Vesicles > Flashcards

Vesicles Flashcards

1
Q

Transport vesicles

A

Transport vesicles carry cargo form lumen and membrane of donor compartment to lumen and membrane of target compartment

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2
Q

Transport vesicles are coated in

A

Protein

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3
Q

Protein coated functions

A

1- curve the membrane to form vesicle
2- select the components to be carried

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4
Q

Vesicle coat is —— protein layers

A

Two
Outer later
Inner layer

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5
Q

Outer layer protein coat

A

Cage around vesicle

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6
Q

Inner layer protein coat

A

Adapter between outer and lipid bilayer
**select cargo proteins through affinity interactions

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7
Q

Classes of coated vesicles

A

1- CopII coated vesicles
——move materials forward from ER to ERGIC/anterograde
2- CopI coated vesicles
——move materials backward from ERGIC to ER/retrograde
3- Clathrin coated vesicles
——move materials from plasma membrane backward to endosome OR trans golgi to endosome

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8
Q

Budding is initiated by

A

Small GTP protein (GTPase)
SAR1-GDP

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9
Q

SAR1-GDP

A

GEF (guanine exchange factor) replace GDP with GTP causing conformational shift which sticks it into membrane

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10
Q

Sar1-gtp recruits

A

Sec23 and Sec24

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11
Q

Sec 23-24 dimer ———

A

Have a curved conformation, start bending the membrane

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12
Q

Sec 24 act as

A

Adaptor protein
Recruit protein to forming vesicle

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13
Q

Sec 24 act as

A

Adaptor protein
Recruit protein to forming vesicle

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14
Q

—— and —— binds to form cage like outer layer

A

Sec13 and sec31

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15
Q

COPII outer layer

A

Simple lattice
Convergence of four sec13-sec31 dimers

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16
Q

V-SNARE

A

Crucial for fusion of the vesicles to correct target membrane

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17
Q

Once COPII is assembled

A

Budding vesicle will separate from ER membrane

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18
Q

After separation

A

Protein coat must disassemble
Release component to cytosol
This allow v-SNARE to target the vesicle to proper membrane

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19
Q

Protein coat disassembly is mediated by

A

Hydrolysis of GTP, producing sar1-gdp

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20
Q

Vesicle travel can be mediated by

A

Microtubules
Locomotive (motor protein) pulling cargo(vesicles) on railroad(microtubule)

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21
Q

Initial contact between vesicle and target membrane involves

A

Tethering proteins

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22
Q

Two group of tethers

A

1- Rod-shaped fibrous proteins that form long bridges
2- Multi-protein complexes that hold membranes together

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23
Q

Much of membrane viscle/target is conferred by

A

Rab GTPases

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24
Q

Rab-GTP

A

Recruit cytosolic tether protein to membrane surface
Recruits motor protein to vesicle to facilitate transport

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25
SNARE proteins mediate
Fusion between vesicles and target membranes —sorting and targeting uses two families of SNAp REceptors: 1-v-SNARE 2-t-SNARE
26
v-SNARE found on
Vesicles
27
t-SNARE FOUND ON
Target membrane
28
v- and t- SNARE are
Complementary molecules Their alpha helices tightly intertwine and pull membranes together
29
After fusion v- and t- SNARE are still
Tightly associates and in same membrane Need NSF and SNAPS to pry apart the SNAREs using energy
30
COPI-coated vesicle forming is
Similar to COPII-coated Use different coat
31
Endocytic pathway
Exocytosis and Endocytosis In steady state with each other
32
Exocytosis
1- approach secretory vesicle to plasma membrane 2- fusion of membrane 3- rupture plasma membrane 4- discharge vesicle contents 5- vesicle membrane integrated into plasma membrane
33
Endocytosis
1- membrane form a pocket contain materials from exterior 2- membrane closes, forming a vesicle 3- vesicle separate from plasma membrane
34
Some Vesicles after budding out from TGN
Move directions to cell surface and exocytosis **consecutive secretion**
35
Consecutive secretion may requires
Tags
36
Regulated secretion pathway
1- immature bud out from TGN 2- maturation = condensation 3- mature secretary vesicle move close to site of secretion 4- membrane fusion is triggered by hormonal or chemical signal
37
Polarized secretion
Specific proteins needs to be secreted from a limited region of plasma membrane
38
Polarized secretion is common in
Nerve cells Intestinal cells
39
Proteins and lipids destined for polarized secretion are
Sorted into vesicles with receptors to bind the localized region **temporary regulated**
40
Exocytosis
Proteins are released to exterior of the cell *proteins and lipid for membrane use exocytosis*
41
Bulk-phase Endocytosis
Primates ways that cell maintain membrane and fluid balance Clarithin-independent Endocytosis Doesn’t ingest particular molecules—non-specific
42
Endocytosis (Receptor-Mediated Endocytosis)
Cell can selectively and efficiently acquire macromolecules by receptor-mediated Endocytosis Use receptor on outer cell to internalize hormones
43
Receptor-Mediated Endocytosis
1-Ligands bind to their receptors on outer cell surface 2-receptor-ligand diffuse latterly 3-they encounter specialized region called coated pits
44
Triskelion
Clathrin molecule consist of 3 heavy chains and 3 light chains
45
Clathrin-coated vesicles
Clathrin molecules extensively overlap, while COPII do not
46
Assembly clathrin cage is promoted
Adapter protein 2
47
Dynamin
Cytosolic GTPases Required for constricting the clathrin vesicle
48
Ingestion of large (>500nm) macromolecules or whole organisms is called
Phagocytosis
49
Phagocytosis in human
Mostly restricted to WBC
50
Endocytic vesicles then fuse with——— to degrade the target
endosome/lysosome
51
Lysosomes
Destroys endosomes(materials after endocytosis)
52
Acid hydrolase
Hydrolytic enzyme with ph=5 —capable of degrading all major classes of macromolecules
53
Lysosomes have highly acidic lumen
-maintain an acidic environment -lower PH is caused by v-type ATPase that pump proton inside
54
Endocytic vesicle
Vesicle budding from plasma membrane as result of bulk-phase or receptor-mediated endocytosis
55
Early endosome
Primary sorting station in endocytic pathway Material either recycled back or targeted for degradation
56
Late endosome
Organelle contain full compliment of acid hydrolase but kymen has not reached ph4-5
57
Lysosome
An organelle that is digestively active
58
Routes from late endosome to lysosome
1-ATPase pump cam lower the ph, which active the enzyme and generate lysosome 2-Late endosome fuse with existing lysosome
59
Endocytosis of two type of receptors
1- housekeeping receptors 2- signaling receptors
60
Housekeeping receptors mediate
the uptake of material that will used by cell **receptor will deliver the bound material in early endosome, releasing it because of the lower affinity at lower ph, then return to the cell membrane**
61
Signaling receptor bind
Extracellular messengers that change activity of cell Receptors will degraded, reducing the sensitivity of the cell
62
Phagocytic vacuoles material degradation
Phagocytic vacuoles become lysosoms by fusion with endosome
63
Vesicles formed by receptor-mediated endocytosis ———
Fuse with vesicles of TGN contain acid hydrolase
64
Indigestible materials
Will leave the cell Lysosome become residual body
65
Nutrients of digestion
Can leave the cell(exocytosis) Or Release nutrient as digestion happens to the cell
66
Autophagy
Digestion of old organelles and cell structures
67
Autophagy types
Macrophagy Microphagy
68
Macrophagy
Formation autophagic vacoule (autophagosome) when an organelle become wrapped in double membrane from ER
69
Microphagy
Smaller vacuole is formed surrounded by single membrane

Mbb231 (19 decks)

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