In vitro exocytosis in sea urchin eggs requires a synaptobrevin-related protein

Abstract

Sea urchin eggs provide an efficient in vitro model of exocytosis. We have identified proteins in sea urchin eggs that cross-react with antibodies to mammalian synaptobrevin, synaptotagmin, SNAP-25, syntaxin and rab3a. We show that these proteins are localized to the sea urchin egg cortex, using western blotting and immunocytochemistry. Tetanus toxin light chain cleaves the synaptobrevin-related protein in vitro and inhibits calcium-induced exocytosis. These data demonstrate a conservation between phyla of protein sequence and molecular mechanisms thought to facilitate exocytosis and show that the sea urchin egg provides a unique in vitro exocytotic model with which to study the conserved protein machinery of membrane fusion during secretion.

SNAP23 is required for constitutive and regulated exocytosis in mouse oocytes†

“…Regulated exocytosis has been studied to some extent in eggs of a variety of species. Sea urchin eggs contain homologs of mammalian secretory proteins [18], and inhibition of the SNARE synaptobrevin (VAMP) inhibits cortical granule exocytosis [19]. In porcine eggs, cortical granules associate with SNAP23, syntaxin 2, and VAMP1 [20], but the function of these SNARE proteins has not been examined in detail.…”