Structural highlights
Publication Abstract from PubMedgamma-Aminobutyric acid type A (GABA(A)) receptors mediate fast inhibitory signaling in the brain and are targets of numerous drugs and endogenous neurosteroids. A subset of neurosteroids are GABA(A) receptor positive allosteric modulators; one of these, allopregnanolone, is the only drug approved specifically for treating postpartum depression. There is a consensus emerging from structural, physiological and photolabeling studies as to where positive modulators bind, but how they potentiate GABA activation remains unclear. Other neurosteroids are negative modulators of GABA(A) receptors, but their binding sites remain debated. Here we present structures of a synaptic GABA(A) receptor bound to allopregnanolone and two inhibitory sulfated neurosteroids. Allopregnanolone binds at the receptor-bilayer interface, in the consensus potentiator site. In contrast, inhibitory neurosteroids bind in the pore. MD simulations and electrophysiology support a mechanism by which allopregnanolone potentiates channel activity and suggest the dominant mechanism for sulfated neurosteroid inhibition is through pore block. Structural insights into opposing actions of neurosteroids on GABA(A) receptors.,Legesse DH, Fan C, Teng J, Zhuang Y, Howard RJ, Noviello CM, Lindahl E, Hibbs RE Nat Commun. 2023 Aug 22;14(1):5091. doi: 10.1038/s41467-023-40800-1. PMID:37607940[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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