Actin and Actin-Binding Proteins

Abstract

Organisms from all domains of life depend on filaments of the protein actin to provide structure and to support internal movements. Many eukaryotic cells use forces produced by actin polymerization for their motility, and myosin motor proteins use ATP hydrolysis to produce force on actin filaments. Actin polymerizes spontaneously, followed by hydrolysis of a bound adenosine triphosphate (ATP). Dissociation of the g-phosphate prepares the polymer for disassembly. This review provides an overview of the properties of actin and shows how dozens of proteins control both the assembly and disassembly of actin filaments. These players catalyze nucleotide exchange on actin monomers, initiate polymerization, promote phosphate dissociation, cap the ends of polymers, cross-link filaments to each other and other cellular components, and sever filaments. Outline 1 Introduction 2 Genes, sequence conservation, distribution, and abundance 3 Structures of actin and actin filaments 4 Nucleotide binding and polymerization 5 Overview of actin-binding proteins 6 Actin-monomer-binding proteins 7 Severing proteins 8 Nucleation proteins 9 Actin filament polymerases 10 Capping proteins 11 Cross-linking proteins 12 Filament-binding proteins 13 Concluding