Thermodynamics of calmodulin binding to cardiac and skeletal muscle ryanodine receptor ion channels |
| |
Authors: | Meissner Gerhard Pasek Daniel A Yamaguchi Naohiro Ramachandran Srinivas Dokholyan Nikolay V Tripathy Ashutosh |
| |
Affiliation: | Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260, USA. meissner@med.unc.edu |
| |
Abstract: | The skeletal muscle (RyR1) and cardiac muscle (RyR2) ryanodine receptor calcium release channels contain a single, conserved calmodulin (CaM) binding domain, yet are differentially regulated by CaM. Here, we report that high-affinity [(35)S]CaM binding to RyR1 is driven by favorable enthalpic and entropic contributions at Ca(2+) concentrations from <0.01 to 100 microM. At 0.15 microM Ca(2+), [(35)S]CaM bound to RyR2 with decreased affinity and binding enthalpy compared with RyR1. The rates of [(35)S]CaM dissociation from RyR1 increased as the temperature was raised, whereas at 0.15 microM Ca(2+) the rate from RyR2 was little affected. The results suggest major differences in the energetics of CaM binding to and dissociation from RyR1 and RyR2. |
| |
Keywords: | Ca2+ release channel sarcoplasmic reticulum ryanodine receptor binding enthalpy binding entropy |
本文献已被 PubMed 等数据库收录! |
|