Tropomyosin isoforms show unexpected differential effects on actin polymerization

Abstract

Tropomyosin is a rod-like coiled-coil protein that forms a continuous filament that is weakly associated, but firmly-attached to the surface of the actin filaments in all eukaryotic cells. Simple eukaryotes such as yeasts have only one or two different tropomyosin isoforms which are known to be essential and perform roles in regulating the actin cytoskeleton. However higher eukaryotes have larger numbers of tropomyosins, the number of which appear linked to organismal complexity. Mammals have 4 genes producing over 40 different isoforms by alternative splicing.