Calcium channel that mediates the release of Ca(2+) from the sarcoplasmic reticulum into the cytoplasm in muscle and thereby plays a role in triggering muscle contraction. May regulate Ca(2+) release by other calcium channels. Calcium channel that mediates Ca(2+)-induced Ca(2+) release from the endoplasmic reticulum in non-muscle cells. Contributes to cellular calcium ion homeostasis (By similarity). Plays a role in cellular calcium signaling. Homotetramer. Heterotetramer with RYR2. Interacts with CALM (By similarity). Interacts with FKBP1A. Interacts with SELENON (By similarity). The number of predicted transmembrane domains varies between orthologs, but both N-terminus and C-terminus seem to be cytoplasmic. Brain, skeletal muscle, placenta and possibly liver and kidney. In brain, highest levels are found in the cerebellum, hippocampus, caudate nucleus and amygdala, with lower levels in the corpus callosum, substantia nigra and thalamus. The calcium release channel activity resides in the C-terminal region while the remaining part of the protein resides in the cytoplasm. Channel activity is modulated by the alkaloid ryanodine that binds to the open calcium-release channel with high affinity. At low concentrations, ryanodine maintains the channel in an open conformation. High ryanodine concentrations inhibit channel activity. Channel activity is regulated by calmodulin (CALM). The calcium release is activated by elevated cytoplasmic calcium levels in the micromolar range, by caffeine and adenine nucleotides, such as AMP and ATP. Inhibited by Mg(2+) and ruthenium red (By similarity). Belongs to the ryanodine receptor (TC 1.A.3.1) family. RYR3 subfamily. Ryanodine receptor entry