Regulatory light chain, myosin

The regulatory light chains of myosin are known to be phosphorylated at different serine and threonine residues. Thr-18 and Ser-19 are substrates of the myosin light chain-kinase (MLCK) whereas Ser-1, Ser-2 und Ser-9 are phosphorylated by the protein kinase C (PKC) (Naka et al., 1988 Kawamoto et al., 1989 Moussavi et al., 1993). As the first slow phosphorylation by the MLCK is already present in the 

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S ATP -I- myosin regulatory light chain <12-14> (<12-14> catalytic domain... 

Bornhauser BC, Olsson P-A, Lindholm D. 2003. MSAP is a novel MIR-interacting protein that enhances neurite outgrowth and increases myosin regulatory light chain. J Biol Chem 278 35412-35420. 

Olsson P-A, Korhonen L, Mercer EA, Lindholm D. 1999. MIR is a novel ERM-like protein that interacts with myosin regulatory light chain and inhibits neurite outgrowth. J Biol Chem 274 36288-36292. 

Figure 11.3 Localization of the phosphorylation sites of cortactin (A and B) and the myosin regulatory light chain (RLC C, D).

In smooth muscle, contraction is controlled by the phosphorylation state of the myosin regulatory light chain. The extent of this phosphorylation will depend on the regulatory states of both myosin light chain kinase (MLCK) and of... 

Contraction of smooth muscle and nonmuscle cells Is triggered by phosphorylation of the myosin regulatory light chains either by myosin LC kinase. In response to a rise In cytosolic Ca ", or by Rho kinase, in response to external signals (see Figure 19-25). 

FIGURE 5 Comparison of amino acid sequence for myosin regulatory light chain proteins in different species. Cce, chicken cellular LC20-A, chicken adult smooth muscle LC20-B1, chicken embryonic smooth muscle Ram, rat aortic muscle Hsm, putative human smooth muscle. Amino acid residues are numbered starting at the Ser residue next to the initiator Met. A dot indicates identity of an amino acid residue with that in the top row. Reproduced with permission from Zavodny et al. (1990, Fig. 3, p. 937), Copyright 1994, American Heart Association. 

Pharmacomechanical coupling was primarily studied by measuring [Ca +J and myosin regulatory light chain phosphorylation in intact and skinned smooth muscle. Several groups found that stimuli increased... 

A. Ca + Dependence of Myosin Regulatory Light Chain Phosphorylation... 

Liu, G. P.C. Newell. 1994. Regulation of myosin regulatory light chain... 

Inoue, A., Yanagisawa, M. Masaki, T. (1992). Differential tissue expression of multiple genes for chicken smooth muscle/nonmuscle myosin regulatory light chains. Biochim. Biophys. Acta, 1130, 197-202. 

Zhang, H., Wessels, D., Fey, P. et al. (2002). Phosphorylation of the myosin regulatory light chain plays a role in motility and polarity during Dictyostelium chemotaxis. y. Cell Sci. 115, 1733—1747. 

Hopkins, S.C., Sabido-David, C., Coirie, J.E., Irving, M. and Goldman, Y.E. (1998). Fluorescence polarization transients from rhodamine isomers on the myosin regulatory light chain in skeletal muscle fibers. Biophys. J. 74 3093-3110. 

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