The RyR functions as a calcium release channel. Upon stimulation, such as by an action potential in muscle cells, the receptor opens to allow the flow of Ca2+ from the sarcoplasmic reticulum into the cytoplasm. This increase in cytoplasmic Ca2+ concentration initiates the interaction between the actin and myosin filaments, leading to muscle contraction. The RyR also plays a role in calcium homeostasis by regulating intracellular Ca2+ levels.
