Consensus phosphorylation sites of human GABA(c)/GABArho receptors are not critical for inhibition by protein kinase C activation.
The mechanism of inhibition of human GABA(C)/GABArho receptors by protein kinase C (PKC) activation was investigated in Xenopus oocytes. Phorbol 12-myristate 13 acetate (PMA), a potent PKC activator, at 25 nM inhibited the currents through GABArho2 receptors, which have one consensus phosphorylation site by PKC in the predicted intracellular loops. The time-courses and amplitudes of inhibition were not significantly different from those occurring through GABArho1 receptors, which have six such sites. The inhibitory effect of PMA was also observed after removing each consensus phosphorylation site in both GABArho1 and rho2 receptors by site-directed mutagenesis. These results suggest that phosphorylation of consensus sites in the intracellular loops is not involved in the inhibition of human GABA(C)/GABArho receptors by PKC activation.
Kusama
T
T
Department of Physiology and Anatomy, Nihon University College of Pharmacy, Funabashi, Chiba, Japan.
Hatama
K
K
Sakurai
M
M
Kizawa
Y
Y
Uhl
G R
GR
Murakami
H
H
D000818:Animals; D016384:Consensus Sequence / Q000502:physiology*; D004553:Electric Conductivity; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D018079:Receptors, GABA / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014982:Xenopus laevis
C087200:GABA-C receptor; D018079:Receptors, GABA; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate