Hyaluronidase PH-20 precursor (EC 3.2.1.35) (Hyal-PH20) (Sperm surface protein PH-20) (Sperm adhesion molecule 1); Involved in sperm-egg adhesion. Upon fertilization sperm must first penetrate a layer of cumulus cells that surrounds the egg before reaching the zona pellucida. The cumulus cells are embedded in a matrix containing hyaluronic acid which is formed prior to ovulation. This protein aids in penetrating the layer of cumulus cells by digesting hyaluronic acid (511 aa)