Elongation phase

short oligomer rapidly increases in length by the addition of actin monomers to both of its ends, causing filament elongation

TLS Online TPP Program

#Id: 8332

#XL - Q Biochemistry

Latrunculin, 

a toxin secreted by sponges, binds and sequesters G-actin

TLS Online TPP Program

#Id: 8331

#XL - Q Biochemistry

Cytochalasin D, 

a fungal alkaloid, depolymerizes actin filaments by binding to the (+) end of F-actin.

TLS Online TPP Program

#Id: 8330

#XL - Q Biochemistry

TLS Online TPP Program

#Id: 8329

#XL - Q Biochemistry

Treadmilling

Because the critical concentrations for the two ends are different, at steady state the free ATP–G-actin will be intermediate between Cc+ and Cc - , so the (+)end will grow and the (-)end will lose subunits.

TLS Online TPP Program

#Id: 8327

#XL - Q Biochemistry

TLS Online TPP Program

#Id: 8326

#XL - Q Biochemistry

The two ends of microfilament polymerize at different rates:

fast-growing end - plus end

slow-growing end - minus end