Modulation of large conductance Ca2+-activated K+ channel by Galphah (transglutaminase II) in the vascular smooth muscle cell.
Among G-proteins, Gh is unique in structural differences in the GTP-binding domain and possessing transglutaminase activity. We have studied the role of G protein in modulation of large conductance Ca2+-activated K+ (Maxi-K+) channel by the inside-out mode of patch clamp in smooth muscle cells from superior mesenteric artery of the rabbit. When the non-hydrolyzable GTP analogue, GTPgammaS, was applied, the channel activity was increased about 2.5-fold. Addition of GDPbetaS resulted in reversal of the GTPgammaS effect. When the Galphah7 antibody was applied, the GTPgammaS-stimulated channel activity was significantly inhibited to control level, suggesting that Galphah is involved in activation of the Maxi-K+ channel in smooth muscle cells.
Lee
M Y
MY
Departments of Physiology and Biochemistry, College of Medicine, Chung-Ang University, Seoul 156-756, Korea.
Chung
S
S
Bang
H W
HW
Baek
K J
KJ
Uhm
D
D
D000818:Animals; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D051036:Large-Conductance Calcium-Activated Potassium Channels; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011817:Rabbits; D011503:Transglutaminases / Q000378:metabolism*
D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins