Nonmuscle actin-binding proteins

Nonmuscle Actin-Binding Proteins Drugs Affecting Actin Polymerization Patterns of Arrangement of Actin Filaments in Animal Cells Three-Dimensional Networks The Microtrabecular Lattice... 

More than 50 proteins have been discovered in the cytosol of nonmuscle cells that bind to actin and affect the assembly and disassembly of actin filaments or the cross-linking of actin filaments with each other, with other filamentous components of the cytoskeleton, or with the plasma membrane. Collectively, these are known as actin-binding proteins (ABPs). Their mechanisms of actions are complex and are subject to regulation by specific binding affinities to actin and other molecules, cooperation or competition with other ABPs, local changes in the concentrations of ions in the cytosol, and physical forces (Way and Weeds, 1990). Classifications of ABPs have been proposed that are based on their site of binding to actin and on their molecular structure and function (Pollard and Cooper, 1986 Herrmann, 1989 Pollard et al., 1994). These include the following ... 

Various nonmuscle forms of myosin also interact with actin without formation of the myofibrils of muscle.299 In most higher organisms nonmuscle myosins often consist of two 200-kDa subunits plus two pairs of light chains of 17 and 24 kDa each. These may form bipolar aggregates, which may bind to pairs of actin filaments to cause relative movement of two parts of a cell.303 Movement depending upon the cytoskeleton is complicated by the presence of a bewildering array of actin-binding proteins, some of which are listed in Table 19-1. 

Caldesmon is a major actin binding protein associated with thin filament of smooth muscle (Sobue etal., 1981) and nonmuscle cells (Owada and Kakiuchi,... 

Ohishi I, Hama Y (1992) Purification and characterization of heterologous component lls of botulinum C2 toxin. In Microbiol Immunol. 36 221 -9 Ohishi I, Iwasaki M, Sdkaguchi G. (1980) Purification and characterization of two components of botulinum 02 toxin. In Infect Immun. 30 668-73 Ohishi I, Miyake M (1985) Binding of the two components of 02 toxin to epithelial cells and brush borders of mouse intestine. In Infect Immun. 48 769-75 Ohishi I, Tsuyama S (1986) ADP-ribosylation of nonmuscle actin with component I of 02 toxin. In Biochem Biophys Res Comm. 136 802-6 Ohishi I, Yanagimoto A (1992) Visualizations of binding and internalization of two nonlinked protein components of botulinum 02 toxin in tissue culture cells. In Infect Immun. 60 4648-55... 

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