A cAMP-dependent regulatory protein for RLC-a myosin kinase catalyzing the phosphorylation of scallop smooth muscle myosin light chain.

摘要: A cAMP-dependent regulatory protein which modulates the phosphorylation of scallop myosin light chain-a (RLC-a) by RLC-a kinase (aMK) (Sohma, H. & Morita, F. (1986) J. Biochem. 100, 1155-1163) was purified from smooth muscle. is abundant in opaque portion muscle, one catch muscles. The for aMK employing successively DEAE Toyopearl ion exchange chromatography, Sepharose 4B-8(6-aminohexylamino)cAMP affinity and Sephadex G 100 gel filtration. molecular mass 41 kDa, based on mobility polyacrylamide electrophoresis presence sodium dodecyl sulfate. With increasing amounts protein, activity decreased, complete inhibition observed at concentration twice that aMK. inhibited restored addition cAMP. These results suggest similar to a catalytic subunit kinase, reported here its subunit. may exist as an inactive form, combination with this vivo be deinhibited increase intracellular We discuss possible correlation between catalyzed state