Subnanometer-resolution Electron Cryomicroscopy-Based Domain Models for the Cytoplasmic Region of Skeletal Muscle RyR Channel

Proc Natl Acad Sci U S A. 2008 Jul 15;105(28):9610-5. doi: 10.1073/pnas.0803189105. Epub 2008 Jul 10.

Abstract

The skeletal muscle Ca(2+) release channel (RyR1), a homotetramer, regulates the release of Ca(2+) from the sarcoplasmic reticulum to initiate muscle contraction. In this work, we have delineated the RyR1 monomer boundaries in a subnanometer-resolution electron cryomicroscopy (cryo-EM) density map. In the cytoplasmic region of each RyR1 monomer, 36 alpha-helices and 7 beta-sheets can be resolved. A beta-sheet was also identified close to the membrane-spanning region that resembles the cytoplasmic pore structures of inward rectifier K(+) channels. Three structural folds, generated for amino acids 12-565 using comparative modeling and cryo-EM density fitting, localize close to regions implicated in communication with the voltage sensor in the transverse tubules. Eleven of the 15 disease-related residues for these domains are mapped to the surface of these models. Four disease-related residues are found in a basin at the interfaces of these regions, creating a pocket in which the immunophilin FKBP12 can fit. Taken together, these results provide a structural context for both channel gating and the consequences of certain malignant hyperthermia and central core disease-associated mutations in RyR1.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cryoelectron Microscopy*
  • Cytoplasm
  • Models, Molecular*
  • Muscle, Skeletal / chemistry
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Ryanodine Receptor Calcium Release Channel / chemistry*

Substances

  • Ryanodine Receptor Calcium Release Channel