Enhancement of smooth muscle contraction with protein phosphatase inhibitor 1: Activation of inhibitor 1 by cGMP-dependent protein kinase

Toshiya Tokui, Frank Brozovich, Shoji Ando, Mitsuo Ikebe

Research output: Contribution to journalArticle

12 Scopus citations


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 β-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.

Original languageEnglish (US)
Pages (from-to)777-783
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - Mar 27 1996


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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