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Flashcards in vesicular traffic 2 Deck (27):
1

What are ER exit sites?

specialized site without ribosomes that bud off and takes cargo to intermediate vesicle

2

How are cargo proteins recognized by COPII?

by exit signals on cargo proteins or their receptors (for soluble proteins)

3

How does ER resident proteins exit?

by slow leaking

4

What happens to COPII components after delivering their cargo?

They are recycled and reused

5

What are some examples for protein receptors that COPII recognize?

ERGIC53 -receptor for blood clotting factors V and VIII lack of these receptors cause excessive bleeding

6

What happens to misfolded or incompletely assembled proteins?

That are retained by chaperones

7

What type of signals or the peptide sequences recognized by COPII?

DI acidic
hydrophobic

8

What is homotypic fusion?

ER derived vesicles fusing with one anther to form vesicular tubular clusters (VTC)

9

What are vesicular tubular clusters?

vesicles carrying cargo to the golgo

10

What is fusion mediated by?

Tsnares and Vsnares
contributed by both membranes

11

How does vesicular tubular clusters (VTC) move to the golgi?

microtubule tracks

12

What is the retrieval transport of ER?

vesicles that bud off VTC and GA are COPI

13

What are ER retrieval signals?

signals that COPI bind to retrieve and bring back to the ER

14

What are some ER retrieval signals?

KKXX - membrane proteins
and a KDEL sequence for soluble proteins

15

How doe COPI bind to the KKXX membrane protein retrieval signal?

it binds directly to this signal

16

How does COPI bind to the KDEL soluble protein retrieval signal?

It binds via a KDEL receptor

17

How is the KDEL soluble protein receptor change for the KDEL sequence?

KDEL receptor has a higher affinity for KDEL sequence at lower (ACIDIC conditions) pH.
KDEL receptor wil be found near the (VTC & GA)

AT neutral PH it has a lower affinity. will be found near the ER

18

What is kin recognition?

A KDEL independent mechanism for ER boun proteins
they bind to each other

19

What doe the Golgi apparatus consist of?

4-6 flattened membrane enclosed cisternae

20

What are the sides of the Golgi apparatus?

cis face (entry face)
medial
trans face (exit face)
with two distinct networks -cis golgi network (intermediate compartment)
trans golgi network (TGN)

21

Where is the GOLGI located?

near the nucleus and close to the centrosome
localization depends on microtubules

22

Where does COPI also sort?

Forward from the TGN

23

Where are oligosacharide chains processed at?

the golgi

24

Where are the proteoglycans also initiated at?

the golgi

25

What is O linked glycosylation?

adding to the hydroxyl groups of serine and threonine side chains

26

What is O linked glycosylation catalyzed by?

glycosyl transferase

27

What is the purpose of glycosylation?

increase protein solubility
provide signals for chaperones :glyco code
become resistant to digestion
cell to cell recognition abd communication
cell to cell adhesion

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