The inositol 1,4,5-trisphosphate receptor (Itpr) gene family in Xenopus: Identification of type 2 and type 3 inositol 1,4,5-trisphosphate receptor subtypes

Studies in the Xenopus model system have provided considerable insight into the developmental role of intracellular Ca²⁺ signals produced by activation of IP₃Rs (inositol 1,4,5-trisphosphate receptors). However, unlike mammalian systems where three IP₃R subtypes have been well characterized, our molecular understanding of the IP₃Rs that underpin Ca²⁺ signalling during Xenopus embryogenesis relate solely to the original characterization of the 'Xenopus IP₃R' cloned and purified from Xenopus laevis oocytes several years ago. In the present study, we have identified Xenopus type 2 and type 3 IP₃Rs and report the full-length sequence, genomic architecture and developmental expression profile of these additional IP₃R subtypes. In the light of the emerging genomic resources and opportunities for genetic manipulation in the diploid frog Xenopus tropicalis, these data will facilitate manipulations to resolve the contribution of IP₃R diversity in Ca²⁺ signalling events observed during vertebrate development.