Purification and characterization of smooth muscle myosin-associated phosphatase from chicken gizzards.

摘要: Myosin light chain phosphatase associated with smooth muscle myosin (MAPP) was isolated from chicken gizzard. The MAPP tightly and not dissociated under the physiological ionic conditions. in presence of high MgCl2, i.e. 80 mM MgCl2. binding site enzyme on molecule subfragment-2 region, since did bind to rod heavy meromyosin but subfragment-1 affinity column. purified a heparin-Sepharose 6B column, two activity peaks were obtained, I II. major peak, I, further homogeneity by thiophosphorylated chain-Sepharose 4B column chromatography. tetramer composed four 34-kDa subunits. preferentially dephosphorylated beta-subunit phosphorylase kinase strongly inhibited heat- acid-stable protein inhibitor-1, whereas it partially inhibitor-2. IC50 (concentration inhibitor giving 50% inhibition) value for inhibition okadaic acid 70 nM which about eight times higher than skeletal type-1 390 type-2 phosphatase. These results demonstrate that is type-1-like phosphatase, although properties are same as type-I myosin-associated distinct phosphatases reported previously, some similar phosphatase-IV. Therefore, concluded novel Since myosin, likely responsible dephosphorylation situ.