The oviduct is a dynamic organ which modulates gamete physiology. Sperm-oviduct interaction provides the formation of a sperm storage reservoir and allows the selection of sperm with certain qualities in eutherian mammals. In sows, the oviductal sperm binding glycoprotein (SBG) has been proposed to be involved in sperm selection. In this work, based on its affinity to sperm periacrosomal membrane proteins, we isolate another pig oviductal cell protein that interacts with sperm. Peptide identification by LC/MS-MS allowed the identification of this protein as annexin A2. The presence of this annexin, as well as annexin A1 and annexin A5 in sow oviductal cells was confirmed by Western blot with specific antibodies. The three proteins were localized in sow oviduct by immunohistochemistry, showing the presence of annexin A2 at the apical surface of the oviductal epithelial cells. Based on our data and the fact that annexins have been stated as candidate receptors of bovine sperm for sperm reservoir formation, we propose that this family of proteins is involved in sperm-oviduct interaction, annexin A2 being the main sperm binding isoform in pig.
(c) 2008 Wiley-Liss, Inc.