S100A7 is present in human sperm and a homologous pig sperm protein interacts with sperm-binding glycoprotein (SBG)

In sows, the oviductal sperm-binding glycoprotein (SBG), which binds to the periacrosomal region of boar sperm, has been shown to be involved in sperm selection. In this work, we isolated porcine sperm proteins that interact with SBG. One of them is identified as a homologue of human S100A7 (psoriasin). Anti-human S100A7 antibodies show that this homologous protein localises to the head of sperm. The isolation of a homologue of S100A7 based on affinity to SBG and its localisation at the head of sperm leads us to suggest that S100A7's homologous protein may be involved in the negative selection of sperm by SBG in pigs. Human S100A7 shows antibacterial properties, particularly over Escherichia coli, a species that has demonstrated deleterious effects on human sperm. We searched for S100A7 in human sperm and found that it is present and localises at the acrosomal region. Thus, we report the presence of S100A7 in human sperm and of a homologous protein in pig, with similar localisations. In humans, an antimicrobial role seems likely for psoriasin; in porcine sperm the studied protein binds to SBG suggesting a function in sperm selection, but an antimicrobial function cannot be ruled out.