Lecture 1

Question 1

Constitutive Secretion

Answer 1

• Most cargo moves through constitutive secretion
• No specific signals
• Clathrin coated vesicles can return membrane back to Golgi

Question 2

Regulated Secretion

Answer 2

• Regulated secretion vesicles fully formed but do not fuse with plasma membrane until signal is received

Question 3

Endocytosed proteins have 3 options

Answer 3

• Recycling to same domain of plasma membrane
• Transcytosis to other domain of plasma membrane
• Degradation

Question 4

Clathrin

Answer 4

• Mediate vesicle formation in cytoplasm
• Endocytosis

Question 5

Vesicle Coats

Answer 5

• COPII moves from ER -> golgi -> extracellular space
• COP1: Endosome -> Golgi -> ER
• Clathrin: Golgi to endosomes

Question 6

SNARE proteins

Answer 6

• Mediate vesicle fusion(exocytosis)
• Both t and v SNARES required: must be on opposite membranes

Question 7

ESCRT

Answer 7

• Form vesicles away from cytoplasm
• ESCRT 0 bind to PI(3)P and ubiquitinated signaling receptor with ligand attached -> form intralumenal vesicle

Question 8

Phosphoinositides

Answer 8

• Label different membrane domains
• PI(4,5)P2 target clathrin coat assembly
  - Adaptor proteins bind PI(4,5)P2, cargo, and clathrin
• In early endosome: Rab5-GTP recruit PI3-kinase, PI(3)P recruit Rab5-GEF, More Rab5-GEF makes more active Rab5-GTP
• Rabs and SNARES work together in vesicle targeting and fusion