Hyaluronidase PH20/Hyaluronidase-5 (IPR001439)

Short name: Hyaluronidase_PH20/Hyal5

Overlapping homologous superfamilies

Family relationships

  • Hyaluronidase (IPR018155)
    • Hyaluronidase PH20/Hyaluronidase-5 (IPR001439)


O-Glycosyl hydrolases (EC:3.2.1.) are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [PMID: 7624375, PMID: 8535779]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site.

Family 56 (GH56) encompasses a group of hyaluronidases (EC: that includes venom hyaluronidases and mammalian sperm surface proteins (PH-20 and hyaluronidase-5) [PMID: 16330764, PMID: 19605784].

PH-20 is required for sperm adhesion to the egg zona pellucida; it is located on both the sperm plasma membrane and acrosomal membrane [PMID: 2269661]. During fertilisation, 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. PH-20 facilitates penetration of the cumulus cell layer by digesting hyaluronic acid [PMID: 8282124]. The amino acid sequence of the mature protein contains approximately 460 amino acids, and includes six potential N-linked glycosylation sites and twelve cysteines, eight of which are tightly clustered near the C terminus [PMID: 2269661].

GO terms

Biological Process

GO:0007342 fusion of sperm to egg plasma membrane involved in single fertilization

Molecular Function

GO:0004415 hyalurononglucosaminidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.