Analysis of substance capable of binding with inositol-1, 4,5-triphosphate (IP.sub.3) receptor (IP.sub.3R), preferably with a regulation domain of IP.sub.3R; analysis of the function of IP.sub.3R; and establishing of a method of treatment or diagnosis for various malfunctions and diseases associated with IP.sub.3R. In particular, control of the activity of intracellular Ca.sup.2+ release. More specifically, a regulator for the activity of inositol-1,4, 5-triphosphate (IP.sub.3) receptor (IP.sub.3R), comprised of carbonic anhydrase related protein (CARP); a control agent for intracellular calsium release, comprised of carbonic anhydrase related protein (CARP); and a method of control therewith.