THE EFFECT OF SUBUNIT COMPOSITION OF RAT-BRAIN GABA-A RECEPTORS ON CHANNEL FUNCTION

Different combinations of cloned rat brain subunit isoforms of the GABAA receptor channel were expressed in Xenopus oocytes. The voltage-clamp technique was then used to measure properties of the GAGA-induced membrane currents and to study the effects of various modulators of the GABAA receptor channel (diazepam, DMCM, pentobarbital, and picrotoxin). This approach was used to obtain information on the minimal structural requirements for several functional properties of the ion channel. The combination α5β2γ2 was identified as the minimal requirement reproducing consensus properties of the vertebrate GABAA receptor channel, including cooperativity of GABA-dependent channel gating gating with a Ka in the range of 10 μM, modulation by various drugs acting at the benzodiazepine binding site, picrotoxin sensitivity, and barbiturate effects. © 1990.