Confocal microscopic study of GABA(A) receptors in Xenopus oocytes after rat brain mRNA injection: modulation by tyrosine kinase activity

The expression of GABAA receptors in Xenopus oocytes injected with rat brai n mRNA was studied by immunocytochemistry and evaluation of the distributio n of fluorescent probes at the confocal microscope. The beta (2/3) subunit distributed exclusively on the membrane at the animal pole of the oocytes. Treatment of oocytes for 20 min with the protein tyrosine kinase inhibitor genistein, 200 muM, resulted in a lower presence of GABA(A) receptors on th e membrane. The inactive genistein analogue daidzein, 200 muM, had no effec t even with a 30 min treatment. Alkaline phosphatase but not a protein tyro sine phosphatase, when injected into oocytes, reduced GABA receptor membran e expression. The data indicate that protein tyrosine phosphorylation modul ates the expression on the plasma membrane of presynthesized GABAA receptor s. (C) 2001 Elsevier Science B.V. All rights reserved.