Lecture 9 - Intracellular Vesicular Traffic

Question 1

Vesicular transport: Compartments

Answer 1

Donor compartment: holds cargo
Target compartment: receives cargo

Question 2

Vesicular transport: Pathways

Answer 2

Endocytic pathway

Biosynthetic-secretory pathway

Retrieval pathway (retrograde)

Question 3

Endocytic pathway features, fates

Answer 3

Between cell exterior, early endosome, late endosome, and lysosome

Fates:
- recycling
- transcytosis
- degradation

Question 4

Biosynthetic secretory pathway features

Answer 4

Between ER and golgi, golgi and exterior, secretory vesicles, early endosome, late endosome, late endosome and lysosome

Regulated secretory pathway has signal i.e. specialized secretory cells/released factors (cargo secretion regulated)
Constitutive secretory pathway has no signal (constant delivery/release of cargo)

Question 5

Retrieval pathway features

Answer 5

Between cell exterior and early endosome, early endosome and golgi, sec vesicles and golgi, late endosome and golgi, golgi and ER

Question 6

General role of vesicle coat proteins

Answer 6

Different coat proteins select different cargo, and coat protein function can be modified by forming complexes w/ additional proteins

Clatherin: endocytic vesicles

COPI coated vesicles bud from golgi

COPII coated vesicles bud from ER

Question 7

General role of phosphoinositides

Answer 7

Different types of phosphoinositides are associated w/ different vesicular transport events, usually by serving as binding sites for adaptor proteins found in different vesicle compartments of the cell

Question 8

General role of Rabs in vesicle transport.

Answer 8

Rab GTPases are G proteins that regulate coat assembly and vesicle trafficking

Attach to Rab effector tethering proteins

Question 9

Mechanism of vesicle fusion with target membrane, proteins involved (i.e., v- and t-SNARES).

Answer 9

v-SNARES found on vesicle (ex: synaptobrevin)

t-SNARES found on target membrane (ex: syntaxin)

tether to each other

Question 10

Endocytosis determinant summary:

Answer 10

• Coat proteins
• Phosphoinositides
• Rab GTpases
• v and t-SNARES