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.