Gene Function

The RYR1 gene provides instructions for making a protein called ryanodine receptor 1. This protein is part of a family of ryanodine receptors, which form channels that transport positively charged calcium atoms (ions) within cells. Channels made with the ryanodine receptor 1 protein play a critical role in muscles used for movement (skeletal muscles).

For the body to move normally, skeletal muscles must tense (contract) and relax in a coordinated way. Muscle contractions are triggered by the flow of positively charged ions, including calcium, into muscle cells.

When muscles are at rest, calcium ions are stored in a cellular structure called the sarcoplasmic reticulum inside each muscle cell. In response to certain signals, the RYR1 channel releases calcium ions from the sarcoplasmic reticulum into the surrounding cell fluid (cytoplasm). The resulting increase in calcium ion concentration stimulates muscle fibers to contract, allowing the body to move. The process by which certain chemical signals trigger muscle contraction is called excitation-contraction (E-C) coupling.

Mutations in the RYR1 gene cause the RYR1 channel to open more easily and close more slowly in response to certain drugs. As a result, large amounts of calcium ions are released from storage within muscle cells. An overabundance of available calcium ions causes skeletal muscles to contract abnormally, which leads to muscle rigidity in people with malignant hyperthermia. An increase in calcium ion concentration within muscle cells also activates processes that generate heat (leading to increased body temperature) and produce excess acid (leading to acidosis).

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