ABSTRACT
This chapter discusses the structure of the actin molecule and the subtle process by which it self-assembles into filaments. It describes the ways in which the cell controls filament formation, including the remarkable example of Listeria bacteria, which highjack the polymerization machinery for their own ends. The chapter examines the family of actin-binding proteins and mention some of their functions that underpin cell movements. It explains that there are proteins that recognize one end or the other of an actin filament, and that the two ends have different rates of polymerization. The chapter shows that the conformational change induced by nucleotide hydrolysis causes the two ends of the actin filament to undergo essentially different binding reactions, with different critical concentrations for actin subunits. Actin filaments permeate the interior of eucaryotic cells, providing an interface with the cytosol that is much greater in extent than that of cell membranes.
