Cysteine-rich secretory proteins (CRISPs) represent a family of evolutionarily conserved proteins which may play a role in the innate immune system and are transcriptionally regulated by androgens in several tissues. AEG is a sperm surface protein involved in the fusion of egg and sperm. Although CRISP-1 (also designated AEG-like protein, ARP, cysteine-rich secretory protein-1 or AEG-related protein) is not the ortholog of rodent AEG, it resembles AEG in that it is an epididymal secretory glycoprotein that binds to the postacrosomal region of the sperm head. CRISP-1 coats the postacrosomal region of sperm heads as they pass through the epididymis. CRISP-1 is found in all regions of the epididymis, ductus deferens, seminal plasma and sperm. CRISP-3 is expressed in pancreas and prostate tissues and, along with CRISP-1, is expressed in saliva.
