Affordable Access

A recently identified member of the glutathione transferase structural family modifies cardiac RyR2 substate activity, coupled gating and activation by Ca2+ and ATP

Authors
Publisher
Portland Press Ltd.
Publication Date
Source
PMC
Keywords
  • Research Article
Disciplines
  • Biology

Abstract

bic982.dvi Biochem. J. (2005) 390, 333–343 (Printed in Great Britain) doi:10.1042/BJ20042113 333 A recently identified member of the glutathione transferase structural family modifies cardiac RyR2 substate activity, coupled gating and activation by Ca2+ and ATP Angela F. DULHUNTY1, Pierre POULIQUIN, Marjorie COGGAN, Peter W. GAGE and Philip G. BOARD Division of Molecular Bioscience, John Curtin School of Medical Research, P.O. Box 334, Canberra, ACT 2601, Australia The recently discovered CLIC-2 protein (where CLIC stands for chloride intracellular channel), which belongs to the ubiquitous glutathione transferase structural family and is expressed in the myocardium, is a regulator of native cardiac RyR2 (ryanodine re- ceptor 2) channels. Here we show that recombinant CLIC-2 increases [3H]ryanodine binding to native and purified RyR chan- nels, enhances substate activity in individual channels, increases the number of rare coupled gating events between associated RyRs, and reduces activation of the channels by their primary endogenous cytoplasmic ligands, ATP and Ca2+. CLIC-2 (0.2– 10 µM) added to the cytoplasmic side of RyR2 channels in lipid bilayers depressed activity in a reversible, voltage-independent, manner in the presence of activating (10–100 µM) or sub-activ- ating (100 nM) cytoplasmic Ca2+ concentrations. Although the number of channel openings to all levels was reduced, the fraction and duration of openings to substate levels were increased after exposure to CLIC-2. CLIC-2 reduced increases in activity induced by ATP or adenosine 5′-[β,γ -imido]triphosphate. Depression of channel activity by CLIC-2 was greater in the presence of 100 µM cytoplasmic Ca2+ than with 100 nM or 10 µM Ca2+. Further, CLIC-2 prevented the usual ∼50-fold increase in activity when the cytoplasmic Ca2+ concentration was increased from 100 nM to 100 µM. The results show that CLIC-2 interacts with the RyR protein by a mechanism that does not require oxidation, but is influenced by a conserved Cys residue at

There are no comments yet on this publication. Be the first to share your thoughts.

Statistics

Seen <100 times
0 Comments
F