title: PHI-1 induced enhancement of myosin phosphorylation in chicken smooth muscle.
abstract: Herein, we provide evidence that in chicken smooth muscle, G-protein stimulation by a Rho-kinase pathway leads to an increase in myosin light chain phosphorylation. Additionally, G-protein stimulation did not increase MYPT1 phosphorylation at Thr695 or Thr850, and CPI-17, was not expressed in chicken smooth muscle. However, PHI-1 was present in chicken smooth muscle tissues. Both agonist and GTP(gamma)S stimulation result in an increase in PHI-1 phosphorylation, which is inhibited by inhibitors to both Rho-kinase (Y-27632) and (PKC) GF109203x. These data suggest that PHI-1 may act as a CPI-17 analog in chicken smooth muscle and inhibit myosin phosphatase activity during G-protein stimulation to produce Ca2+ sensitization.
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
authors.forename: Amr
authors.initials: A
authors.lastname: El-Touhky
authors.forename: Allison M
authors.initials: AM
authors.lastname: Given
authors.forename: Audrey
authors.initials: A
authors.lastname: Cochard
authors.forename: Frank V
authors.initials: FV
authors.lastname: Brozovich
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002645:Chickens; D019204:GTP-Binding Proteins / Q000819:agonists*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D013912:Threonine / Q000378:metabolism
chemical_list: D000577:Amides; D007211:Indoles; D008301:Maleimides; D018994:Myosin Light Chains; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D011506:Proteins; D011725:Pyridines; C073882:phosphoprotein phosphatase inhibitor 1; C108830:Y 27632; D013912:Threonine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D011493:Protein Kinase C; D043263:Myosin-Light-Chain Phosphatase; D019204:GTP-Binding Proteins; C070515:bisindolylmaleimide I; D002118:Calcium