F-actin sructure, dynamics and networks

Question 1

How is an actin filament structure formed?

Answer 1

Actin subunits -> oligomers -> growing actin filament (only forms when actin is in ATP state) -> actin filament with subunits coming on and off

Question 2

Example of monomer binding proteins

Answer 2

Profilin - Charges actin up to ATPactin

Question 3

Example of filament severing protein

Answer 3

Cofilin - Actin destabiliser

Question 4

Example of filament capping protein

Answer 4

Cap2 - Binds at + end = disassembly

Tropomodulin - Prevents disassembly at - end

Question 5

Example of filament nucleators

Answer 5

Formin - straight, multidomain protein, activated when recruited to plasma membrane = filament formation
Arp2/3 complex - branched, nucleates assembly to form web

Question 6

Example of bundling proteins

Answer 6

Fimbrin - Microvilli formed by closely packed actin filaments by fimbrin + short cross-linking proteins

Question 7

Example of cross linking protein

Answer 7

Filamin - Creates a mesh for stability.