The subtypes of the mouse inositol 1,4,5-trisphosphate receptor are expressed in a tissue-specific and developmentally specific manner

Additional subtypes of the inositol 1,4,5-trisphosphate (InsP₃) receptor are expressed in a tissue-specific and developmentally specific manner. They differ from the InsP₃ receptor structure previously reported in two small variably spliced segments. One segment (SI) is located within the InsP₃ binding site, whereas another segment (SII) is located near putative sites for phosphorylation and ATP binding to modulate InsP₃ action on Ca²⁺ flux. Therefore, we speculate that selective use of InsP₃ receptor subtypes permits a tissue-specific and developmentally specific expression of functionally distinct channels.