ZIMA questions lecture 5

Question 1

________: proteins are transported by endosomes from the ER to the PM or lysosomes aka outward

_______: proteins are transported from PM and delivered to endosomes and lysosomes - inward

_______: balancing in the opposite direction, bringing membrane and selected proteins to compartment of origina

Answer 1

Exocytosis

Endocytosis

Retrieval Pathway

Question 2

Vesicular transport is mediated by _______

Before the vesicles fuse with the membrane they______

Answer 2

Vesicular transport is meadiated by coated vesicles

Before the vesicles fuse with the membrane they discard their coat

Question 3

What are the two main functions of the coat around vesicles

Answer 3

Two main functions of the coat:

1. it concentrates specific membrane proteins in a specialized patch
2. it forms the vesicle

Question 4

Clathirin coated vesicles are involved in____

COP I and COP II are in volved in _____

Answer 4

Clathirin: ENDOcytosis

COPI and COPII: EXOcytosis

Question 5

______ is the major protein of coated vesicles

Structure:

Answer 5

Clathirin is the major protein of clathirin coated vesicles

Clathirin forms a triskelion (six subunits)

Question 6

______ binds clathirin coat to the cargo receptors

Answer 6

ADAPTOR proteins bind clathirin to the cargo receptors (it goes cargo protein –> receptor–> adaptor protein–> clathirin)

Question 7

Without an adaptor protein will the vesicle form?

Answer 7

NO without an adaptor protein the vesicle cannot form

Question 8

__________ have important regulatory function in vesicular trafficking.

Answer 8

Phosphoinosites (PIPs) have important regulatory function in vesicular trafficking.

PIPs can undergo phosphorylation and dephosphorylation

Question 9

The distribution of different PIPs varies from organelle to organnele

The PIP binding proteins help regulate_____

Answer 9

The PIP binding proteins help regulate vesicle formation and transport.

Question 10

What structure plays an important ole in PINCHING off of clathirin vesicles

Answer 10

PINCHING off of vesicles: dynamin

dynamin uses GTP to squeeze bilayer and pinch it off

Question 11

Explain how vesicles are uncoated:

After releasing the vesicle loses its clathirin coat:

1. ________ that are co-packaged into vesicles depletes, weakining the binding of adaptor protein and diassembles clathirin
2. Additionally, the hydrolysis of ___ on ____ causes the coat to diassemble
3. _____ protein acts as the uncoating ATPase

Answer 11

1. PIP phosphotases deplete phosphates from the membrane, weakining the binding of adaptor proteins and diassembles clathirin
2. Additionally, the hydrolysis of GTP in Sar1 protein causes the vesicle coat to disassemble
3. Hsp 70 chaperone protein acts as uncoating ATPase

Question 12

What structure directs the vesicles to specific spots on the target membrane?

Answer 12

RAB proteins direct vesicles to specific spots on the target membrane

Question 13

What MEDIATES the fusion of the lipid bilayer

Answer 13

SNARE MEDIATES fusion

Question 14

What protein is the TETHERING protein to the target membrane

Answer 14

RAB EFFECTORS tether the vesicle to the membrane

Question 15

V snare vs T snare

transSNARE complex

Answer 15

V snare (single chain)

T snare (many chains)

V and T come together to form a transSNARE complex

Question 16

What protein diassembles the SNARE complex?

Answer 16

NSF protein diassembles the SNARE complex

Question 17

HIV first binds with the _____ protein on the target cell. The viral ____ protein mediates the interaction.

Then ___ receptor interacts to release the HIV fusion protein.

Answer 17

HIV first binds to the CD4 protein on the surface of the target cell. The viral gp120 protein, which is bound to the HIV fusion protein mediates this interaction. Then, chemokines receptor interacts with gp120 to release the HIV fusion protein.