ITPR3A gene on chromosome 6p21 that encodes an intracellular receptor for a so-called second messenger (inositol 1,4,5-trisphosphate (IP3)), which, once stimulated by IP3, mediates calcium release from the endoplasmic reticulum. The three IP3 receptor subtypes—IP3R1, IP3R2 and IP3R3—are present in the wild as homo- and heterotetramers, are associated with calmodulin and FK506-binding protein, and are modulated through phosphorylation by PKA, PKC, PKG and CaMKII. ITPR2 and ITPR3 are thought to play a role in exocrine secretion during metabolism and growth.
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