Identification of calponin as a novel substrate of Rho-kinase

Takako Kaneko, Mutsuki Amano, Akio Maeda, Hideyuki Goto, Katsuhito Takahashi, Masaaki Ito, Kozo Kaibuchi

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107 Citations (Scopus)


Calponin, an F-actin-associated protein implicated in the regulation of smooth muscle contraction, is known to be phosphorylated in vitro by protein kinase C (PKC) and Ca2+/calmodulin dependent protein kinase II (CaM kinase II). Unphosphorylated calponin binds to F-actin and inhibits the actin-activated myosin ATPase activity; these properties are lost on phosphorylation. In the present study, we found that Rho-kinase phosphorylated basic calponin stoichiometrically in vitro. We identified the sites of phosphorylation of calponin by Rho-kinase as Thr-170, Ser-175, Thr-180, Thr-184, and Thr-259, and prepared antibodies that specifically recognized calponin phosphorylated at Thr-170 and Thr-184. We showed that the phosphorylation of calponin by Rho-kinase inhibited the binding of calponin to F-actin. Taken together, these results suggest that calponin is a substrate of Rho-kinase and that Rho-kinase regulates the interaction of calponin with F-actin. (C) 2000 Academic Press.

Original languageEnglish
Pages (from-to)110-116
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number1
Publication statusPublished - 24-06-2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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