MOLECULAR-CLONING OF MADM - A CATALYTICALLY ACTIVE MAMMALIAN DISINTEGRIN-METALLOPROTEASE EXPRESSED IN VARIOUS CELL-TYPES

A peptide sequence of a metalloprotease purified from bovine brain [Ch antry, Gregson and Glynn (1989) J, Biol. Chem. 264, 21603-21607] was u sed to design an oligonucleotide probe for screening a bovine brain cD NA library, A contig of the two overlapping cDNA clones that were isol ated encoded a 748-amino-acid polypeptide with similarity to the disin tegrin-metalloprotease precursor proteins of haemorrhagic snake venom. The bovine protein has been named MADM, for mammalian disintegrin-met alloprotease. The predicted mature protein has 534 amino acids arrayed as extracellular metalloprotease and disintegrin (potential integrin- binding) domains, a transmembrane helix and a basic/proline-rich cytop lasmic C-terminus. Highly conserved homologues of bovine MADM were fou nd in cDNA libraries of rat brain and a human U937 histiocytic lymphom a cell line. A wide variety of mammalian cell lines expressed low leve ls of MADM mRNA (4.5 and 3.2 kb transcripts) and mature polypeptide (M (r) 62000), as assessed by Northern analysis and Western blotting with an antiserum raised to a peptide within the disintegrin domain. MADM appears to be a rather distantly related member of the reprolysin prot ein family, which includes both the snake venom disintegrin-metallopro teases and a number of predicted cell-surface disintegrin-containing m ammalian proteins.