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601 EXAM 1 > 1.9 protein trafficking/targeting > Flashcards

1.9 protein trafficking/targeting Flashcards

1
Q

Proteins needing to be translocated have _____ that direct them to their proper location

A

tags

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2
Q

______ bind to tags and direct the protein to the destination

A

Chaperone proteins

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3
Q

_____ form to allow translocation of proteins into membrane bound organelles

A

Translocon/pores

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4
Q

all protein translation begins in the _____

A

cytosol

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5
Q

proteins entering the secretory pathway target the _____ first then are carried to other compartments by vesicles

A

ER

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6
Q

A ________ recognizes the signal sequence and directs the ribosome to a receptor on the ER.

A

signal recognition particle (SRP)

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7
Q

steps of SRP taking protein to ER

A
  1. SRP attaches to signal sequence on polypeptide chain
  2. SRP guides to SRP receptor in membrane
  3. SRP displaced and recycled
  4. signal sequence docks in ER
  5. polypeptide continues growing through translocation channel
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8
Q

_______ removes the signal sequence, releasing the peptide to form into its correct shape

A

signal peptidase

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9
Q

______ adds sugars during translation

A

Glycosyltransferase

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10
Q

proteins destined to remain in the ER have an AA tag that determines this location called a _____

A

stop transfer sequence (STA)

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11
Q

steps of the synthesis of an integral membrane protein:

A
  1. protein enters translocation channel, with start-transfer sequence caught in the channel
  2. translation continues into the ER lumen
  3. translation stops once the Stop transfer sequence is reached
  4. signal peptidase cleaves the Start transfer sequence
  5. half of protein is left in Lumen and half is in cytosol
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12
Q

what 2 things assist a new protein in its proper folding in the ER?

A

molecular chaperones

folding enzymes

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13
Q

_______ is the process of IDing, reverse translocating, and degrading misfolded ER proteins

A

ER-associated degradation (ERAD)

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14
Q

ERAD consists of :

A

reverse translocation
ubiquitination
proteation

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15
Q

________ is the process by which a carbohydrate (oligosaccharide) is covalently attached to a macromolecule

A

glycosylation

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16
Q

An oligosaccharide that is to be N-linked to a protein begins in the cytosol and is assembled on a ________. It is then translocated to the ER Lumen where more mannose units are added and is then attached to a polypeptide chain

A

dolichol phosphate

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17
Q

Immediately after the oligosaccharide is added to a peptide, what happens?

A

3 glucose residues and 1 mannose residue are removed (signal it is complete)

18
Q

Modification of glycosylated proteins and sorting of proteins to their appropriate domain occur in the golgi and the sorting occurs because of ______ which can be AA sequences, sugar residues, hydrophobicity and size

A

tags

19
Q

N-linkage glycosylation occurs in the _________ while O-linked occurs only in the _____-

A

ER and golgi, ONLY golgi

20
Q

_______ are responsible for selecting cargo and sorting vesicles

A

coatomers/coat proteins

21
Q

_________ mediates cargo recruitment and Anterograde transport which means from the ____to the _____

A

COPII, ER, Golgi

22
Q

_________ mediates cargo recruitment and RETROGRADE transport which means from the ____to the _____

A

COP1, Golgi, ER

23
Q

_______ moves cargo from the golgi/lysosomes/vacuoles out of the cell

A

clathrin

24
Q

Retrieval signals, like one called ________, are recognized by a receptor and causes the protein to be taken back to the ER

A

KDEL

25
Q

The KDEL signal is recognized by _____

A

COP1

26
Q

The ________ toxin has a KDEL sequence so it can appear as a misfolded protein, be taken to the ER, go into the cytosol and fold into an active toxin

A

Cholera

27
Q

______ are vesicle transporters that move INTO the cell and ________ are vesicle transporters that move OUT of the sell

A

dynein, kinesin

28
Q

__________ tether a vesicle to the target membrane and assist with the fusion of their lipid bilayers to achieve vesicle fusion

A

SNARE proteins

29
Q

SNARES also tells a vesicle ______

A

where its going (some snares only interact with other snares)

30
Q

__________ recognizes proteins/enzymes/hydrolases that locate to the lysosome and then add mannose-6-phosphate. the proteins are then bound by the mannose-6-phos (M6P) receptor in the membrane of the ________. The M6P receptor is taken in a vesicle to an endosome. the low pH triggers dissociation of the M69 complex and the activation of the _________, resulting in a mature lysosome

A

GlcNac phosphotransferase
golgi complex
lysosomal enzymes

31
Q

2 pathways for exocytosis

A 
constitutive
regulated (usually in cells specialized for secretion)
32
Q

______ and _____ are translocators that help proteins with a MT sequence enter the mitochondrial matrix

A

TOM, TIM

33
Q

_______ can recognize the MT signal sequence, while _____ can recognize the cystolic chaperone proteins Hsp90 and hsp70. Both of these bring the protein into the mitochondria

A

TOM20, TOM70

34
Q

_______ are embedded into the membranes surrounding the nucleus and allow passive diffusion of small molecules

A

NPCs

35
Q

proteins going to the nucleus contain a _____ and proteins leaving the nucleus have a _____

A
  1. nuclear localization signal

2. nuclear export signal

36
Q

________ binds NLS bearing proteins and acts as an adapter to access the importin B-dependent import pathway

A

importin-a

37
Q

nuclear export of a cargo protein occurs by association of nuclear export signal (NES) with __________ and _______, and then transport through a nuclear pore complex

A

chromosome maintenance protein 1 (CRM1)

RanGTP

38
Q

peroxisomal proteins are targeted to the matrix by the targeting tags ______ & _____.

A

PTS1, PTS2

39
Q

PTS1 containing proteins are recognized by _____

A

Pex7

40
Q

_______ is an ion channel that transports Cl- and bicarbonate across the apical surfaces of epithelia. A defect in this leads to a secretion which becomes very difficult to clear

A

cystic fibrosis transmembrane regulator (CFTR)

601 EXAM 1 (12 decks)

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