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Location of a High Affinity Zn2 Binding Site in the Channel of
 

Summary: Location of a High Affinity Zn2
Binding Site in the Channel of
1 1 -Aminobutyric AcidA Receptors
JEFFREY HORENSTEIN and MYLES H. AKABAS
Center for Molecular Recognition (J.H., M.H.A.) and the Departments of Physiology and Cellular Biophysics (J.H., M.H.A.) and Medicine
(M.H.A.), Columbia University, New York, New York 10032
Received November 10, 1997; Accepted January 16, 1998 This paper is available online at http://www.molpharm.org
ABSTRACT
Zn2
inhibits currents through -aminobutyric acid (GABA)A
receptors. Its affinity depends on the subunit composition;
1 1 receptors are inhibited with high affinity (IC50 0.54 M).
We sought to identify the residues that form this high affinity
Zn2
binding site. 1His267 aligns with 1Ser272, a residue
near the extracellular end of the M2 membrane-spanning seg-
ment that we previously demonstrated to be exposed in the
channel. The Zn2
affinity of 1 1 H267S was reduced by
300-fold (IC50 161 M). Addition of a histidine at the aligned

  

Source: Akabas, Myles - Department of Physiology and Biophysics, Albert Einstein College of Medicine, Yeshiva University

 

Collections: Biology and Medicine