Regulatory light chain

The experiments of Mougios and Barany (1986) supported the idea that the multiple LC20 spots origi- 

Based on the existence of two nonphosphorylated isoforms that can be mono- or diphosphorylated (Barany et al., 1985a Erdodi et al., 1987), the four spots shown in Fig. 3 are explained by the scheme of Fig. 4. As it appears. Spot 2 contains both diphosphorylated and nonphosphorylated isoforms, which is the reason for the four stained and three radioactive spots. 

Zavodny et al. (1990) have isolated two series of cDNAs from a chicken gizzard cDNA library encoding 

Watanabe et al. (1992) sequenced chemically the LC20 of porcine aorta myosin. There was only one amino acid substitution compared with chicken gizzard and two substitutions compared with human umbilical artery smooth muscle LC20. It is noteworthy that the substitutions never take place at positions 18 and 19, the phosphorylation sites for MLCK, or at positions 1, 2, and 9, the phosphorylation sites for PKC. 

The finding that the nonmuscle LC20 content in porcine carotid artery (16 3% of the total LC20) matches that of nonmuscle myosin HC content (14 2%) raised the question of a specific function of nonmuscle myosin isoforms (Gaylinn et al., 1989). On the other hand, the proportion of nonmuscle LC20 to 

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This kinase specifically phosphorylates the regulatory light chain of myosin after activation by calcium-calmodulin. Several isozymes of approximately 135 kDa exist. 

Smooth muscle myosin contains two myosin light chains. Phosphorylation of the regulatory light chain by myosin light chain kinase is a mandatory step to induce contraction. 

The regulatory light chains from vertebrate forms of myosin-II undergo reversible phosphorylation by a calmodulin dependent enzyme called myosin light chain... 

A986P <1> (<1> significantly increase in Ca required for half-maximal activity, slightly decreased Km for regulatory light chain [49]) [49]... 

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. 

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... 

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... 

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