Abstract
IP₃ receptor is a Ca(2+) release channel localized on the endoplasmic reticulum. IP(3) receptor is composed of three isoforms, which are expressed in various cells and tissues, and play variety of roles throughout development. I here describe the role of IP₃ receptor from oogenesis, meiotic maturation and fertilization. I also describe the Ca(2+) signaling at meiosis and mitosis, and especially the role in early embryogenesis to determine dorso-ventral axis formation. Loss of function mutation of type 1 IP₃ receptor in mouse, both by gene targeting and spontaneous mutations shows severe ataxia and other phenotypes. Interestingly, double knockouts of type 1 and type 2 exhibit cardiogenesis arrest and that of type 2 and type 3 results in exocrine secretion deficit. IP₃R of Drosophila or Caenorhabditis elegans is single gene and mutation results severe phenotype of behavior. All the data described here show that IP₃Rs are essential for life and abnormality of IP(3)Rs results in severe abnormality in its structure and function of organism.
