title: Regulation of myosin phosphatase through phosphorylation of the myosin-binding subunit in platelet activation.
abstract: Human platelets were found to contain myosin phosphatase consisting of a 38-kD catalytic subunit of protein phosphatase type 1delta, a 130-kD myosin-binding subunit (MBS) and a 20-kD subunit, all of which cross-reacted with antibodies against these subunits of smooth muscle myosin phosphatase. Anti-MBS antibody coimmunoprecipitated RhoA and Rho-kinase of human platelets. Platelets MBS is a substrate for Rho-kinase and phosphorylation of MBS decreases the activity of myosin phosphatase. Treatment of intact platelets with 9, 11-epithio-11,12-methano-thromboxane A2 led to a dramatic increase in phosphorylation of MBS and a significant decrease in the activity of myosin phosphatase. These findings suggest a putative mechanism for agonist-induced regulation of myosin phosphatase activity in platelets.
authors.affiliation: 2nd Department of Internal Medicine, Mie University School of Medicine, Tsu Mie, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakai
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Kihira
authors.forename: H
authors.initials: H
authors.lastname: Wada
authors.forename: M
authors.initials: M
authors.lastname: Fujioka
authors.forename: M
authors.initials: M
authors.lastname: Ito
authors.forename: T
authors.initials: T
authors.lastname: Nakano
authors.forename: K
authors.initials: K
authors.lastname: Kaibuchi
authors.forename: H
authors.initials: H
authors.lastname: Shiku
authors.forename: M
authors.initials: M
authors.lastname: Nishikawa
mesh_terms: D001665:Binding Sites; D001792:Blood Platelets / Q000378:metabolism*; D006801:Humans; D043263:Myosin-Light-Chain Phosphatase; D009218:Myosins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D015539:Platelet Activation
chemical_list: D010749:Phosphoprotein Phosphatases; D043263:Myosin-Light-Chain Phosphatase; D009218:Myosins