Acrosin

Acrosin is a digestive is_associated_with::enzyme that acts as a is_associated_with::protease. In humans, acrosin is encoded by the ACR is_associated_with::gene. Acrosin is released from the is_associated_with::acrosome of is_associated_with::spermatozoa as a consequence of the is_associated_with::acrosome reaction. It aids in the penetration of the is_associated_with::Zona Pellucida.

Function
Acrosin is the major proteinase present in the acrosome of mature spermatozoa. It is a typical serine proteinase with trypsin-like specificity. It is stored in the acrosome in its precursor form, proacrosin. The active enzyme functions in the lysis of the zona pellucida, thus facilitating penetration of the sperm through the innermost glycoprotein layers of the ovum. The mRNA for proacrosin is synthesized only in the postmeiotic stages of spermatogenesis. In humans proacrosin first appears in the haploid spermatids.