Activation of the G protein Gq/11 through tyrosine phosphorylation of the alpha subunit.
Various receptors coupled to the heterotrimeric guanine nucleotide-binding protein Gq/11 stimulate formation of inositol-1,4,5-trisphosphate (IP3). Activation of these receptors also induces protein tyrosine phosphorylation. Formation of IP3 in response to stimulated receptors that couple to Gq/11 was blocked by protein tyrosine kinase inhibitors. These inhibitors appeared to act before activation of Gq/11. Moreover, stimulation of receptors coupled to Gq/11 induced phosphorylation on a tyrosine residue (Tyr356) of the Galphaq/11 subunit, and this tyrosine phosphorylation event was essential for Gq/11 activation. Tyrosine phosphorylation of Galphaq/11 induced changes in its interaction with receptors. Therefore, tyrosine phosphorylation of Galphaq/11 appears to regulate the activation of Gq/11 protein.
Umemori
H
H
Department of Oncology, Institute of Medical Science, University of Tokyo, Tokyo 108, Japan.
Inoue
T
T
Kume
S
S
Sekiyama
N
N
Nagao
M
M
Itoh
H
H
Nakanishi
S
S
Mikoshiba
K
K
Yamamoto
T
T
D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D019833:Genistein; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007529:Isoflavones / Q000494:pharmacology; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000378:metabolism*; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D015398:Signal Transduction
D004791:Enzyme Inhibitors; D007529:Isoflavones; D011950:Receptors, Cholinergic; D018094:Receptors, Metabotropic Glutamate; D019000:Phosphotyrosine; D015544:Inositol 1,4,5-Trisphosphate; D002217:Carbachol; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins; D002118:Calcium