Membrane Fusion

Question 1

• What is subcellular protein targeting? When this goes wrong? Ex?
• Basic principles of fusion: Automatically fuse? Must remove what first? What else is important?
• 3 Snare Proteins:
  1? Structure? Located on?
  2? Structure? Location?
  3? Structure? Location?
• Binding rule?
• Same for every pathway? Why?
• Steps of fusion? (3)

Answer 1

• vessicle transport; incorrect transport; CF
• No; remove water first; high specificity
  1: VAMP: Transmembrane domain and helical domain in it –> only vessicles
  2: Syntaxin: Transmembrane and helical domain –> membrane
  3: SNAP25: No transmembrane domains; two helical domains –> membrane
• 3Q:1R
• No; increase specificity
  1. ) Helical domains bind to make tetramer 2.) squeeze water out 3.) Zipper up and overcome repulsion

Question 2

• Role of NSF?
• Role of Sec1?
• Snare cycle? (4)
  Envelope virus fusion: Same process? How many helices? Ex? (3) Specific?
• How does influenza do this?
• How does HIV do this?

Answer 2

• Regulates dissoc. of SNARE after fusion
• Refolds syntaxin after NSF unwinds it
  1. ) Tetramer formed 2.) Lipid fusion 3.) NSF mediated unwinding 4.) SEC1 refolding
• No but similar; 4; Ebola, HIV, Influenza; yes
• Transmembrane domain with hydrophobic fusion domain that refolds with fusion with change in pH
• Targets CD4 and similar method