Involvement of rho in GTP gamma S-induced enhancement of phosphorylation of 20 kDa myosin light chain in vascular smooth muscle cells: inhibition of phosphatase activity.
In beta-escin-permeabilized cultured pig aortic smooth muscle cells GTP gamma S dose-dependently enhances Ca(2+)-induced, wortmannin-sensitive phosphorylation of 20 kDa myosin light chain (MLC20). GTP gamma S does not potentiate thiophosphorylation of MLC20, but does inhibit its dephosphorylation. Pretreatment with C. botulinum exotoxin C3, which specifically ADP-ribosylates and inactivates the rho family of the small molecular weight G proteins, completely abolishes the effects of GTP gamma S. These results indicate that rho is involved in the GTP gamma S-induced enhancement of Ca(2+)-dependent MLC20 phosphorylation in aortic smooth muscle cells, and strongly suggest that this effect of rho is due to inhibition of protein phosphatase activity toward MLC20.
Noda
M
M
Department of Cardiovascular Biology, Faculty of Medicine, University of Tokyo, Japan.
Yasuda-Fukazawa
C
C
Moriishi
K
K
Kato
T
T
Okuda
T
T
Kurokawa
K
K
Takuwa
Y
Y
D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D004928:Escin / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D013552:Swine
D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004928:Escin; D010749:Phosphoprotein Phosphatases; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D009218:Myosins; D002118:Calcium