ADAM20

Disintegrin and metalloproteinase domain-containing protein 20 is an enzyme that in humans is encoded by the ADAM20 gene. It is a membrane disintegrin-metalloprotease that belongs to the ADAM family. It is exclusively expressed in Testes and is similar to sperm cell-specific fertilins -alpha and -beta.

Its cDNA is tightly linked to marker SHGC-36001 on chromosome 14q24.1. ADAM20 is related to fertilin α (ADAM1A/B pseudogene), fertilin β (ADAM2), and fertilin γ (ADAM9). In humans, fertilin α has recently been deactivated so ADAM20 may be the functional equivalent fertilin α in humans.

Structure


In common with other ADAM family members, ADAM20 contains a N-terminal reprolysin family propeptide (residues 57–159), reprolysin (M12B) family zinc metalloprotease domain (207–395), disintegrin domain (416–488), and a C-terminal ADAM cysteine-rich domain (493–605).

The propeptide acts both a signal peptide and an activator domain. This prodomain has a cysteine that interacts with a zinc in the catalytic domain, thereby preventing the catalytic activity of the protein.When the pro-protein domain is cleaved, this cysteine zinc bond is broken and the protein is activated. A notable variant showed an amino acid difference in the pro protein domain that prevented the cleavage of this domain which prevented the fusion of the sperm cell to an egg.