Actin-tropomyosin distribution in non-muscle cells

Abstract

The interactions of cytoskeletal actin filaments with myosin family motors are essential for the integrity and function of eukaryotic cells. They support a wide range of force-dependent functions. These include mechano-transduction, directed transcellular transport processes, barrier functions, cytokinesis, and cell migration. Despite the indispensable role of tropomyosins in the generation and maintenance of discrete actomyosin-based structures, the contribution of individual cytoskeletal tropomyosin isoforms to the structural and functional diversification of the actin cytoskeleton remains a work in progress. Here, we review processes that contribute to the dynamic sorting and targeted distribution of tropomyosin isoforms in the formation of discrete actomyosin-based structures in animal cells and their effects on actin-based motility and contractility.

Keywords: Actin; Actin binding protein; Cytoplasmic protein sorting; Cytoskeleton; Myosin; Tropomyosin.

Fig. 1

Schematic of mammalian tropomyosin genes and known isoforms generated as a result of alternative exon splicing. Coloured boxes represent alternately spliced protein coding exons, black boxes indicate protein coding exons common to all isoforms, lines represent introns and white boxes represent untranslated regions. Commercially available antibodies are noted in blue text underneath their respective epitopes. Isoforms marked with an asterix (*) are cytoplasmic. (Color figure online). Figure adapted from Schevzov et al. (2011). Note that there is evidence for additional isoforms