TLS Online TPP Program

#Id: 8329

#Section 3: Genetics, Cellular and Molecular Biology

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: 8328

#Section 3: Genetics, Cellular and Molecular Biology

Hydrolysis of the bound nucleotide reduces the binding affinity of the subunit for neighbouring subunits and makes it more likely to dissociate from each end of the filament.

T form that adds to the filament and the D form that leaves.

TLS Online TPP Program

#Id: 8327

#Section 3: Genetics, Cellular and Molecular Biology

TLS Online TPP Program

#Id: 8326

#Section 3: Genetics, Cellular and Molecular Biology

The two ends of microfilament polymerize at different rates:

fast-growing end - plus end

slow-growing end - minus end

TLS Online TPP Program

#Id: 8325

#Section 3: Genetics, Cellular and Molecular Biology

Critical concentration (Cc)

minimal concentration of monomers at which filaments form

TLS Online TPP Program

#Id: 8324

#Section 3: Genetics, Cellular and Molecular Biology

The rate of addition of monomers is given by

rate constant kon (M–1 sec–1 )

The rate of loss is given by koff (sec–1)