The identification of seven metalloproteinase-disintegrin (ADAM) genes from genomic libraries

Metalloproteinase-disintegrins (ADAMs) are membrane-spanning multi-domain p roteins containing a zinc metalloproteinase domain and a disintegrin domain which may serve as an integrin ligand. Based on a conserved sequence withi n the disintegrin domain, GE(E/Q)CDCG, seven genes were isolated from a hum an genomic library. Two of these genes lack introns and show testis-specifi c expression (ADAM20 and ADAM21), while the other two genes contain introns (ADAM22 and ADAM23) and are expressed predominantly in the brain. In addit ion, three pseudogenes were isolated; one of which evolved from ADAM21. Hum an chromosomal mapping indicated that ADAM22 and ADAM23 mapped to chromosom e 7q21 and 2q33, respectively, while the three pseudogenes 1-2, 3-3, and 1- 32 mapped to chromosome 14q24.1, 8p23, and 14924.1, respectively. An ancest ral analysis of all known ADAMs indicates that the zinc-binding motif in th e catalytic domain arose once in a common ancestor and was lost by those me mbers lacking this motif. (C) 1999 Elsevier Science B.V. All rights reserve d.