Intracellular calcium channel that is required for proper muscle function during embryonic development and may be essential for excitation-contraction coupling in larval body wall muscles. Homotetramer. The number of predicted transmembrane domains varies between orthologs, but both N-terminus and C-terminus seem to be cytoplasmic. During embryonic stages 9-10, expression is seen in mesoderm of all segments in progenitors of the cephalic and somatic muscles. Adults exhibit high expression in tubular 'jump' muscles of thorax and leg, and lower expression in the brain, ventral ganglion, head muscles and proboscis muscles. Abundant in 6-12 hours embryos, reduced expression in second and third instar larval stages and adults. 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 Ca-release channel with high affinity and maintains the channel in an open conformation. The calcium release channel is modulated by calcium ions, magnesium ions, ATP and calmodulin (By similarity). Belongs to the ryanodine receptor (TC 1.A.3.1) family.