This gene encodes a large, carbohydrate-rich, epithelial glycoprotein with numerous O-glycosylation sites located within threonine, serine, and proline-rich tandem repeats. The gene is similar to members of the mucin and the glycosyl hydrolase 18 gene families. Regulation of expression may be estrogen-dependent. Gene expression and protein secretion occur during late follicular development through early cleavage-stage embryonic development. The protein is secreted from non-ciliated oviductal epithelial cells and associates with ovulated oocytes, blastomeres, and spermatozoan acrosomal regions.