Occupation of either site for the neurosteroid allopregnanolone potentiates the opening of the GABAA receptor induced from either transmitter binding site

John Bracamontes, Megan McCollum, Caroline Esch, Ping Li, Jason Ann, Joe Henry Steinbach, Gustav Akk

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Potentiating neuroactive steroids are potent and efficacious modulators of the GABAA receptor that act by allosterically enhancing channel activation elicited by GABA. Steroids interact with the membrane-spanning domains of the α subunits of the receptor, whereas GABA binds to pockets in the interfaces between β and α subunits. Steroid interaction with a single site is known to be sufficient to produce potentiation, but it is not clear whether effects within the same β-α pair mediate potentiation. Here, we have investigated whether the sites for GABA and steroids are functionally linked (i.e., whether the occupancy of a steroid site selectively affects activation elicited by GABA binding to the transmitter binding site within the same β-α pair). For that, we used receptors formed of mutated concatenated subunits to selectively eliminate one of the two GABA sites and one of the two steroid sites. The data demonstrate that receptors containing a single functional GABA site are potentiated by the neurosteroid allopregnanolone regardless of whether the steroid interacts with the α subunit from the same or the other β-α pair. We conclude that steroids potentiate the opening of the GABAA receptor induced by either agonist binding site.

Original languageEnglish
Pages (from-to)79-86
Number of pages8
JournalMolecular pharmacology
Volume80
Issue number1
DOIs
StatePublished - Jul 2011

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