Membrane fusion

Question 1

How are transport vesicles delivered to the fusion site?

Answer 1

via help of molecular motor proteins that move along actin or microtubule tracks

Question 2

What are the three main classes of SNAREs?

Answer 2

• syntaxins
• VAMPs (vesicle associated membrane protein)
• SNAPs (synaptosome associated protein)

Question 3

What SNAREs are located in the target membrane?

Answer 3

1 syntaxin helices

2 SNAP helices

Question 4

How are SNARE proteins recycled after fusion?

Answer 4

• NSF proteins and alpha-SNAP disassemble SNARE complex

- NSF uses ATP hydrolysis

Question 5

What refolds the SNARE proteins after disassembly?

Answer 5

Sec1 refolds it into the active conformation

Question 6

How do enveloped viruses go through membrane fusion?

Answer 6

viral fusion proteins - contains a transmembrane domain at one end (inserted into the viral membrane) and highly hydrophobic fusion domain (folded and hidden within viral protein). Upon receiving a specific signal, the fusion domain is exposed and inserted into the target cell membrane. Then the fusion protein is refolded, leading to the fusion of the viral and cell membranes