NMD, A NOVEL GENE DIFFERENTIALLY EXPRESSED IN HUMAN-MELANOMA CELL-LINES, ENCODES A NEW ATYPICAL MEMBER OF THE ENZYME FAMILY OF LIPASES

nmd, a novel gene, was isolated by applying the differential mRNA disp lay method to human melanoma cell lines with different metastatic capa city. In a panel of 17 other human tumor cell lines, nmd RNA expressio n could only be detected at low levels in T24 (bladder carcinoma) and Caco-2 (colon adenocarcinoma). Furthermore, it was found in placenta a nd liver, but not in skin, colon, spleen, lung, muscle, prostate and k idney. Sequence analysis classified the nmd gene product as a nea memb er of the enzyme family of lipases (almost 30% identity in amino acid sequence with other human lipases). Active site residues of lipases we re conserved in NMD, but NMD lacks the regulatory lid domain, which co ntrols entry to the active site in classical lipases. A similar deleti on was earlier reported by others in the guinea pig pancreatic (phosph o)lipase GPLRP2 and the phospholipase A1 from hornet venom (DolmI). (C ) 1997 Federation of European Biochemical Societies.