memA/DRS, a putative mediator of multiprotein complexes, is overexpressed in the metastasizing human melanoma cell lines BLM and MV3

memA was isolated by subtractive hybridization in which the mRNA repertoire was compared in a panel of human melanoma cell lines with different metast asizing potential. Expression of memA mRNA is elevated in the highly metast asizing human melanoma cell lines and derived xenografts, as compared with the non-metastasizing ones. In a collection of human tumor cell lines and m elanoma metastasis lesions, memA mRNA expression could be detected in the A -431 (epidermoid carcinoma), HT-1080 (fibrosarcoma), JEG-3 and JAR (chorioc arcinomas) cell lines and in three out of 11 melanoma metastasis lesions. T he distribution of memA mRNA in a collection of healthy human organs is als o tissue restricted. Sequence analysis revealed that the MEMA protein is id entical with a 160 kDa nuclear 'domain rich in serines' (DRS) protein occur ring free in the nucleoplasm and in U2-ribonucleoprotein structures. MEMA i s also homologous to pinin, a 140 kDa protein associated with the desmosome -intermediate filament complex, and to a 32 kDa porcine neutrophilic protei n that was copurified with components of the NADPH-oxidase enzyme complex. The encoded amino acid sequence predicts that the MEMA protein has three co iled-coil domains, one glycine loop domain, is very hydrophilic and contain s regions rich in glutamine/proline, glutamic acid and serine residues. (C) 1999 Elsevier Science B.V. All rights reserved.