By using a synthetic peptide, KM-14, a protein kinase was detected and partially purified from Mougeotia sp. The peptide contains the sequence of the regulatory light chain of smooth muscle myosin that is phosphorylated by calcium-calmodulin-dependent myosin light chain kinase (MLCK). The Mougeotia kinase was stimulated 40-fold by calcium with half-maximal stimulation occurring at 1.5 micromola...

BACKGROUND/AIMS Actin cytoskeleton dynamics support and coordinate signaling events that control cell proliferation, differentiation and migration. Growth factors provide essential signals that act on multi-protein complexes that regulate actin assembly with myosin. We previously analyzed the action of the transforming growth factor β (TGF-β) and now extend our studies to the bone morphogenetic...

The role of myosin light chain phosphorylation in regulating the mechanical properties of the cytoskeleton was studied in NIH/3T3 fibroblasts expressing a truncated, constitutively active form of smooth muscle myosin light chain kinase (tMK). Cytoskeletal stiffness determined by quantifying the force required to indent the apical surface of adherent cells showed that stiffness was increased two...

The myosin holoenzyme is a multimeric protein complex consisting of heavy chains and light chains. Myosin light chains are calmodulin family members which are crucially involved in the mechanoenzymatic function of the myosin holoenzyme. This review examines the diversity of light chains within the myosin superfamily, discusses interactions between the light chain and the myosin heavy chain as w...

All the vertebrate muscle myosins so far investigated have been shown to possess a lightchain component of 18000-20000 molecular weight, the P light chain (Frearson & Perry, 1975), which is phosphorylated by a highly specific enzyme, myosin light-chain kinase (Perrie et al., 1973; Pires et af . , 1974; Frearson & Perry, 1975; Frearson et al., 1976). Studies (Perrie & Perry, 1970; Perry et al., ...

The purpose of this study was to determine the mechanism by which hydrogen peroxide (H2O2), an important inflammatory mediator, relaxes canine tracheal smooth muscle (CTSM). H2O2caused concentration-dependent relaxations of CTSM strips contracted with ACh or isotonic KCl [EC50 of 0.24 ± 0.04 (SE) and 0.23 ± 0.04 mM, respectively]. Indomethacin (10 μM) decreased the sensitivity of both KCl- and ...

Rho-binding kinase and myosin phosphatase regulate the contraction of actomyosin filaments in non-muscle and smooth muscle cells. Previously, we described the role of C. elegans genes encoding Rho-binding kinase (let-502) and myosin phosphatase targeting subunit (mel-11) in epidermal cell-shape changes that drive morphogenesis and in spermathecal contraction. Here we analyze their roles in a th...

Phosphorylation of the regulatory light chains of myosin II (rMLC) by the Ca(2+)/calmodulin-dependent myosin light-chain kinase (MLCK) and dephosphorylation by a type 1 phosphatase (MLCP), which is targeted to myosin by a regulatory subunit (MYPT1), are the predominant mechanisms of regulation of smooth muscle tone. The activities of both enzymes are modulated by several protein kinases. MLCK i...