Actin polymerization and depolymerization in relation to platelet shape change, aggregation and disaggregation

Abstract

Actin is the most abundant platelet protein. It is present in two forms - a globular monomeric form (G-actin), and a filamentous polymeric form (F-actin). The F-actin is present both at the periphery of the cell in the form of a membrane skeleton which helps maintain cell shape, and also contributes to a three dimensional network that exists throughout the cell known as the cytoskeleton.(1) In the resting platelet, G-actin and F-actin exist in equilibrium, but on platelet activation this is disturbed in favour of the production of F-actin, with a corresponding decrease in the amount of G-actin. This process is known as actin polymerization.