Role of Inositol 1,4,5-Trisphosphate Receptor in Ventral Signaling in Xenopus Embryos

Abstract
The inositol 1,4,5-trisphosphate (IP 3 ) receptor is a calcium ion channel involved in the release of free Ca 2+ from intracellular stores. For analysis of the role of IP 3 -induced Ca 2+ release (IICR) on patterning of the embryonic body, monoclonal antibodies that inhibit IICR were produced. Injection of these blocking antibodies into the ventral part of early Xenopus embryos induced modest dorsal differentiation. A close correlation between IICR blocking potencies and ectopic dorsal axis induction frequency suggests that an active IP 3 -Ca 2+ signal may participate in the modulation of ventral differentiation.