Function and modulation of the cloned glycine receptor channels expressed in Xenopus oocytes.

Complementary DNAs encoding glycine receptor subunits alpha 1 and alpha 2 were isolated from rat cDNA libraries. The alpha 2 protein had 71% homology to the alpha 1 protein. The alpha 1 mRNA is abundant in the spinal cord and brain stem of mature rats whereas the alpha 2 mRNA was expressed in the tissues during the restricted period from late embryonic (E18) to early postnatal stage (P10). Homomeric glycine receptor channels consisting of alpha 1 or alpha 2 subunit expressed in Xenopus oocytes had an ability to generate Cl- currents, and the currents were suppressed by strychnine, a selective antagonist. Single channel kinetics between the homomeric channels differed considerably (alpha 1 << alpha 2). The currents generated through homomeric alpha 1 receptor channels were augmented in the presence of Zn2+ (100 nM to 10 microM), and depressed by 4 beta-phorbol 12-myristate 13-acetate (10 nM), an activator of protein kinase C.