Functional properties of recombinant rat GABAA receptors depend upon subunit composition.
GABA-gated chloride channels were expressed in human embryonic kidney cells following transfection of cDNAs encoding the alpha 1, beta 2, and gamma 2 subunits of the rat GABAA receptor (GABAR). Functional properties were determined using patch-clamp techniques in the whole-cell and outside-out configurations. Large whole-cell currents were observed in cells expressing the alpha 1 beta 2, alpha 1 gamma 2, and alpha 1 beta 2 gamma 2 subunit combinations. The unique characteristics of GABAR channels consisting of these subunit combinations depended upon the presence or absence of beta 2 and gamma 3 subunits. GABA-activated currents in cells expressing GABARs with the beta 2 subunit desensitized faster and showed greater outward rectification, and the channels had a shorter mean open time than GABARs composed of alpha 1 gamma 2 subunits. When the gamma 2 subunit was present the resulting GABAR channels had a larger conductance. The slope of the concentration-response curve was significantly steeper for GABARs composed of alpha 1 beta 2 gamma 2 subunits compared with GABARs consisting of alpha 1 beta 2 or alpha 1 gamma 2 subunit combinations.
Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Heidelberg, Federal Republic of Germany.
T A
TA
Verdoorn
A
A
Draguhn
S
S
Ymer
P H
PH
Seeburg
B
B
Sakmann
D000818:Animals; D002460:Cell Line; D018118:Chloride Channels; D002712:Chlorides / Q000502:physiology*; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000502:physiology*; D051381:Rats; D011963:Receptors, GABA-A / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D005680:gamma-Aminobutyric Acid