The structural basis of ryanodine receptor ion channel function.

Area of Science:

• Molecular Biology
• Cellular Physiology
• Biochemistry

Background:

• Large-conductance Ca2+ release channels, ryanodine receptors (RyRs), control Ca2+ release from the endo/sarcoplasmic reticulum.
• Three mammalian isoforms (RyR1, RyR2, RyR3) are critical in skeletal muscle, heart muscle, and various other tissues.
• RyRs form large protein complexes with accessory proteins, featuring conserved C-terminal ion-conducting domains and extensive cytoplasmic regulatory regions.

Purpose of the Study:

• To elucidate the structural basis of ryanodine receptor (RyR) regulation.
• To provide insights into the function of RyRs in different muscle types and tissues.
• To understand the molecular mechanisms underlying Ca2+ release mediated by RyRs.

Main Methods:

• Analysis of near-atomic structures of mammalian skeletal and cardiac muscle RyRs.
• Investigating protein complex composition including RyR subunits, FK506-binding proteins, and accessory proteins.
• Examining experimental evidence for regulatory sites (Ca2+, ATP, phosphorylation, redox) within the RyR structure.

Main Results:

• Near-atomic structures of mammalian skeletal and cardiac RyRs have been determined.
• Structural data provides a basis for understanding the regulation of RyRs by multiple effectors.
• Identified conserved structural features, including the transmembrane ion-conducting domain and the large cytoplasmic regulatory region.

Conclusions:

• The determined structures offer a framework for understanding RyR function and regulation.
• Insights into effector binding and modulation of Ca2+ release are provided.
• This structural information is vital for comprehending muscle contraction, cardiac function, and neurological processes involving Ca2+ signaling.