Involvement of rho p21 in the GTP-enhanced calcium ion sensitivity of smooth muscle contraction

Ken Ichi Hirata, Akira Kikuchi, Takuya Sasaki, Shinya Kuroda, Kozo Kaibuchi, Yoshiharu Matsuura, Hitomi Seki, Kooichi Saida, Yoshimi Takai

Research output: Contribution to journalArticlepeer-review

414 Citations (Scopus)


In the rabbit mesenteric arterial smooth muscle skinned by saponin, Ca2+ induced contraction in a concentration-dependent manner. Guanosine 5′-(3-O thio)triphosphate (GTPγ S), a non-hydrolyzable GTP analogue, lowered the Ca2+ concentrations required for this contraction and increased the Ca2+ sensitivity of the skinned smooth muscle contraction. GTPγS alone did not induce the contraction in the absence of Ca2+. This GTPγS-enhanced Ca2+ sensitivity was completely abolished by an exoenzyme of Staphylococcua aureus, named EDIN, and an exoenzyme of Clostridium botulinum, named C3, both of which are known to ADP-ribosylate the rho p21 family that belongs to the ras p21-like small GTP-binding protein superfamily. The GTPγS-bound form of rhoA p21 overcame the inhibitory action of EDIN. smg p21B, another small GTP-binding protein, was inactive. EDIN ADP-ribosylated a protein, which was most likely to be rho p21, in the skinned smooth muscle. The GTPγS-bound form of rhoA 21, but not the GDP-bound form, substituted for GTPγS and enhanced the Ca2+ sensitivity of the skinned smooth muscle contraction, smg p21B was inactive. These results indicate that rhoA p21 is involved in the GTPγS-enhanced Ca2+ sensitivity of the smooth muscle contraction.

Original languageEnglish
Pages (from-to)8719-8722
Number of pages4
JournalJournal of Biological Chemistry
Issue number13
Publication statusPublished - 05-05-1992
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Involvement of rho p21 in the GTP-enhanced calcium ion sensitivity of smooth muscle contraction'. Together they form a unique fingerprint.

Cite this