a skeletal muscle ryanodine receptor interaction domain in triadin在三合骨骼肌阿诺定受体相互作用域.pdfVIP

A Skeletal Muscle Ryanodine Receptor Interaction Domain in Triadin Elize Wium, Angela F. Dulhunty, Nicole A. Beard* John Curtin School of Medical Research, Australian Capital Territory, Australia Abstract Excitation-contraction coupling in skeletal muscle depends, in part, on a functional interaction between the ligand-gated ryanodine receptor (RyR1) and integral membrane protein Trisk 95, localized to the sarcoplasmic reticulum membrane. Various domains on Trisk 95 can associate with RyR1, yet the domain responsible for regulating RyR1 activity has remained elusive. We explored the hypothesis that a luminal Trisk 95 KEKE motif (residues 200–232), known to promote RyR1 binding, may also form the RyR1 activation domain. Peptides corresponding to Trisk 95 residues 200–232 or 200–231 bound to RyR1 and increased the single channel activity of RyR1 by 1.49 60.11-fold and 1.8 60.15-fold respectively, when added to its luminal side. A similar increase in [3H]ryanodine binding, which reflects open probability of the channels, was also observed. This RyR1 activation is similar to activation induced by full length Trisk 95. Circular dichroism showed that both peptides were intrinsically disordered, suggesting a defined secondary structure is not necessary to mediate RyR1 activation. These data for the first time demonstrate that Trisk 959s 200–231 region is responsible for RyR1 activation. Furthermore, it shows that no secondary structure is required to achieve this activation, the Trisk 95 residues themselves are critical for the Trisk 95-RyR1 interaction. Citation: Wium E, Dulhunty AF, Beard NA (2012) A Skeletal Muscle Ryanodine Receptor Interaction Domain in Triadin. PLoS ONE 7(8): e43817. doi:10.1371/ journal.pone.0043817 Editor: Bradley Steven Launikonis, University of Queensland, Australia Received May 9, 2012; Accepted July