Functional and structural analysis of the GABAA receptor α1 subunit during channel gating and alcohol modulation

Sangwook Jung, Myles Akabas, R. Adron Harris

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The substituted cysteine accessibility method has proven useful for investigating structural changes of the γ-aminobutyric acid type A (GABAA) receptor during channel gating and allosteric modulation. In the present study, the surface accessibility and reaction rate of propyl- and hexyl-methanethiosulfonate to cysteine residues introduced into the third transmembrane segment of the GABAA receptor α1 subunit were examined. GABA-induced currents in Xenopus oocytes expressing wild type and cysteine mutant GABAA receptors were recorded before and after application of methanethiosulfonate (MTS) reagents in the resting, GABA- or alcohol-bound (ethanol or hexanol) states. Our results indicate that a water-filled cavity exists around the Ala291 and Tyr294 residues of the third transmembrane segment, in agreement with previous results. Furthermore, our data indicate that a conformational change produced by alcohols (200 mM ethanol or 0.5 mm hexanol) exposure induces the water cavity around the A291C and Y294C residues to extend deeper, causing the A295C and F296C residues to become accessible to the MTS reagents. In addition, exposure of the A291C, Y294C, F296C, and V297C mutants to MTS reagents in the presence of GABA had significant effects on their GABA-induced currents, indicating that the water cavity around A291C and Y294C residues expanded to F296C and V297C by a structural movement caused by GABA binding. Our data show that GABA A receptor is a dynamic protein during alcohol modulation and channel gating.

Original languageEnglish (US)
Pages (from-to)308-316
Number of pages9
JournalJournal of Biological Chemistry
Volume280
Issue number1
DOIs
StatePublished - Jan 7 2005

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Functional analysis
GABA-A Receptors
Structural analysis
gamma-Aminobutyric Acid
Alcohols
Modulation
Hexanols
Cysteine
Induced currents
Water
Ethanol
Aminobutyrates
Xenopus
Reaction rates
Oocytes
methanethiosulfonate
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Functional and structural analysis of the GABAA receptor α1 subunit during channel gating and alcohol modulation. / Jung, Sangwook; Akabas, Myles; Harris, R. Adron.

In: Journal of Biological Chemistry, Vol. 280, No. 1, 07.01.2005, p. 308-316.

Research output: Contribution to journalArticle

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