Rho-associated kinase of chicken gizzard smooth muscle

Jianhua Feng, Masaaki Ito, Yasuko Kureishi, Kazuhito Ichikawa, Mutsuki Amano, Naoki Isaka, Katsuya Okawa, Akihiro Iwamatsu, Kozo Kaibuchi, David J. Hartshorne, Takeshi Nakano

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223 Citations (Scopus)


Rho-associated kinase (Rho-kinase) from chicken gizzard smooth muscle was purified to apparent homogeneity (160 kDa on SDS-polyacrylamide gel electrophoresis) and identified as the ROKα isoform. Several substrates were phosphorylated. Rates with myosin phosphatase target subunit 1 (MYPT1), myosin, and the 20-kDa myosin light chain were higher than other substrates. Thiophosphorylation of MYPT1 inhibited myosin phosphatase activity. Phosphorylation of myosin at serine 19 increased actin-activated Mg±-ATPase activity, i.e. similar to myosin light chain kinase. Myosin phosphorylation was increased at higher ionic strengths, possibly by formation of 6 S myosin. Phosphorylation of the isolated light chain and myosin phosphatase was decreased by increasing ionic strength. Rhokinase was stimulated 1.5-2-fold by guanosine 5'-O-3(thio)triphosphate-RhoA, whereas limited tryptic hydrolysis caused a 5-6-fold activation, independent of RhoA. Several kinase inhibitors were screened and most effective were Y-27632, staurosporine, and H-89. Several lipids caused slight activation of Rho-kinase, but arachidonic acid (30-50 μM) induced a 5-6-fold activation, independent of RhoA. These results suggest that Rho-kinase of smooth muscle may be involved in the contractile process via phosphorylation of MYPT1 and myosin. Activation by arachidonic acid presents a possible regulatory mechanism for Rho-kinase.

Original languageEnglish
Pages (from-to)3744-3752
Number of pages9
JournalJournal of Biological Chemistry
Issue number6
Publication statusPublished - 05-02-1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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