ADAM20
{{Short description|Protein-coding gene in the species Homo sapiens}}
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Disintegrin and metalloproteinase domain-containing protein 20 is an enzyme encoded by the ADAM20 gene in humans. It is a membrane disintegrin-metalloprotease that belongs to the ADAM family. It is exclusively expressed in the 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 that ADAM20 may be the functional equivalent of fertilin α in humans.{{cite journal | vauthors = Hooft van Huijsduijnen R | title = ADAM 20 and 21; two novel human testis-specific membrane metalloproteases with similarity to fertilin-alpha | journal = Gene | volume = 206 | issue = 2 | pages = 273–82 | date = January 1998 | pmid = 9469942 | doi = 10.1016/s0378-1119(97)00597-0 }}
Structure
File:Final Adam 20 picture for wikipedia article.jpg
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).{{cite web | title = Disintegrin and metalloproteinase domain-containing protein 20 | url = https://www.ebi.ac.uk/interpro/protein/UniProt/O43506/entry/pfam/#table | work = Pfam | via = InterPro }}
The propeptide acts as 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.{{cite journal | vauthors = Van Wart HE, Birkedal-Hansen H | title = The cysteine switch: a principle of regulation of metalloproteinase activity with potential applicability to the entire matrix metalloproteinase gene family | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 87 | issue = 14 | pages = 5578–82 | date = July 1990 | pmid = 2164689 | pmc = 54368 | doi = 10.1073/pnas.87.14.5578 | bibcode = 1990PNAS...87.5578V | doi-access = free }} 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.{{cite journal | vauthors = Sha YW, Xu X, Ji ZY, Mei LB, Qiu PP, Ji H, Li P, Li L, Liu WW | title = Sperm-egg fusion disorder in a Chinese male patient was associated with a rare ADAM20 variant | journal = Oncotarget | volume = 9 | issue = 2 | pages = 2086–2091 | date = January 2018 | pmid = 29416755 | pmc = 5788623 | doi = 10.18632/oncotarget.23331 }}
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