Enhancement of smooth muscle contraction with protein phosphatase inhibitor 1: activation of inhibitor 1 by cGMP-dependent protein kinase.
New method for purification of phosphatase inhibitor 1 (PPI-1) was developed which avoid the phosphorylation of PPI-1 during the purification and provides a high yield of highly pure preparation. Using this preparation, it was shown that PPI-1 was stoichiometrically phosphorylated by cGMP-dependent protein kinase at Thr-35 and the phosphorylated PPI-1 potently inhibited protein phosphatase 1. Addition of the phosphorylated PPI-1 to beta-escin-skinned single smooth muscle cells resulted in force development of the cells at the submaximal pCa2+. The results suggest that the phosphorylation of PPI-1 can be the mechanism for modifying the Ca2+ sensitivity of smooth muscle contractile response.
Tokui
T
T
Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106, USA.
Brozovich
F
F
Ando
S
S
Ikebe
M
M
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins; D002852:Chromatography, Ion Exchange; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D005895:Gizzard, Avian; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010455:Peptides / Q000494:pharmacology; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010766:Phosphorylation; D011169:Portal Vein; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D011817:Rabbits; D014422:Turkeys
D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D010455:Peptides; D010748:Phosphopeptides; D011506:Proteins; C021042:protein phosphatase inhibitor-1; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D009219:Myosin-Light-Chain Kinase