Lecture 13

Question 1

What are the basic features of vesicular transport?

Answer 1

Directional transport via vesicles carrying cargo by budding and fusion

Question 2

Biosynthetic-secretory pathway

Answer 2

Vesicles synthesized and transported within the cell

Question 3

Endocytic pathway

Answer 3

Vesicles are endocytosed from outside the cell and are coming into the cell

Question 4

Retrieval pathway

Answer 4

Vesicles are returning particles to their original compartment

Question 5

What are the 2 major functions of coating for vesicles?

Answer 5

1. Concentrates select proteins for transport

2. Molds vesicle to form to specific shape

Question 6

Where do COPI and COPII mediate transport?

Answer 6

From ER and Golgi cisternae

Question 7

Where do Clathrin-coated vesicles mediate transport?

Answer 7

From Golgi apparatus and plasma membrane

Question 8

Clathrin

Answer 8

Basket-like structure of triskelions that form coated pits on cytosolic side of the membrane

Question 9

Adaptor proteins

Answer 9

Bind clathrin and membrane-bound cargo receptors

Question 10

When is clathrin coat lost?

Answer 10

After vesicle formation is complete

Question 11

Phosphoinositides (PIs)

Answer 11

Control recruitment and binding of proteins to specific organelles/domains; regulate vesicular trafficking

Question 12

BAR domains

Answer 12

Responsible for membrane bending as vesicle is forming

Question 13

Dynamin

Answer 13

Protein that assembles a ring around clathrin bud which tethers (PIP2) and pinches off (GTPase) vesicle

Question 14

What is the role of Hsp70 in the removal of the clathrin coat?

Answer 14

Peels off coat using ATP

Question 15

Rab proteins

Answer 15

Direct vesicle to specific spots on target membrane

Question 16

SNARE proteins

Answer 16

mediate fusion of vesicle with membrane

Question 17

Rab-GDP dissociation inhibitor (GDI)

Answer 17

Keeps Rab in GDP-bound, inactive, soluble form

Question 18

Rab-GEFs

Answer 18

Keep Rab in GTP-bound, active form that is tightly bound to membrane

Question 19

Rab Effectors

Answer 19

Bind active Rab proteins present on target membrane to facilitate tethering and fusion

Question 20

Rab1

Answer 20

Located in ER and Golgi complex

Question 21

Rab2

Answer 21

Located in cis-Golgi network

Question 22

Rab3A

Answer 22

Located in synaptic vesicles, secretory vesicles

Question 23

v-SNAREs

Answer 23

Single polypeptide found on vesicle membrane

Question 24

t-SNAREs

Answer 24

2-3 proteins found on target membranes

Question 25

COPII coated vesicles

Answer 25

Bud off from ER exit sites; proteins display exit signals and recognized by receptors on COPII coat

Question 26

What occurs after vesicles bud from ER exit sites?

Answer 26

Shedding of the coat, fusion of the naked vesicles via SNARE proteins; become vesicular tubular structures

Question 27

What coat is used for vesicles in the retrieval pathway?

Answer 27

COPI

Question 28

KKXX sequence

Answer 28

ER retrieval signal present in ER membrane proteins; interacts with COPI and is packaged into COPI coated vesicles

Question 29

KDEL sequence

Answer 29

ER retrieval signal present in soluble proteins; packages them into COPI coated vesicles

Question 30

Cis-Golgi Network

Answer 30

Fused vesicular tubular clusters arriving from ER (proteins and lipids enter here)

Question 31

Trans-Golgi Network

Answer 31

Region that allows exit of proteins and lipids to next step of secretory pathway

Question 32

Cisternal Maturation Model vs. Vesicle Transport Model

Answer 32

Maturation of Golgi constantly occurring as vesicles are transported vs. Golgi is established structure that vesicles are just moving through; reality: Both