title: Tyrosine kinase phosphorylation of GABAA receptors.
abstract: Phosphorylation of purified bovine brain GABAA receptors by the tyrosine kinase, pp60v-src was examined. pp60v-src phosphorylated two bands of 54-62 kDa and 48-51 kDa that migrated to approximately the same position as bands recognized by antisera against the beta 2 and gamma 2 GABAA receptor subunits, respectively. Bacterially expressed proteins containing the putative large cytoplasmic loops of the beta 1 and gamma 2L subunits were phosphorylated by pp60v-src, indicating that the phosphorylation sites are located in these subunit domains. The tyrosine kinase inhibitors, genistein and the tyrphostins B-42 and B-44, inhibited muscimol-stimulated 36Cl- uptake in mouse brain membrane vesicles (microsacs). magnitude of the tyrphostin B-44-induced inhibition of muscimol-stimulated 36Cl- uptake was significantly reduced in microsacs that were lysed and resealed under conditions that inhibit phosphorylation. GABA-gated Cl- currents were also inhibited by genistein and tyrphostin B-44 in Xenopus oocytes expressing alpha 1 beta 1 and alpha 1 beta 1 gamma 2L subunits. Consequently, protein tyrosine kinase-dependent phosphorylation appears to be another mechanism of regulating the function of GABAA receptors.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002417:Cattle; D002713:Chlorine; D003593:Cytoplasm / Q000648:ultrastructure; D004926:Escherichia coli; D058785:GABA-A Receptor Agonists; D008081:Liposomes; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009118:Muscimol / Q000494:pharmacology; D015688:Oncogene Protein pp60(v-src) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010446:Peptide Fragments / Q000096:biosynthesis / Q000235:genetics*; D010766:Phosphorylation; D011868:Radioisotopes; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis; D014982:Xenopus laevis
chemical_list: D058785:GABA-A Receptor Agonists; D008081:Liposomes; D010446:Peptide Fragments; D011868:Radioisotopes; D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D009118:Muscimol; D002713:Chlorine; D015688:Oncogene Protein pp60(v-src)