Sequence and expression of the cDNA for MEP (major excreted protein), a transformation-regulated secreted cathepsin.
The major excreted protein (MEP) of malignantly transformed mouse fibroblasts is a secreted thiol proteinase. Sequencing of the MEP cDNA shows the coding region for the protein to be identical with the sequence for a mouse cysteine proteinase isolated from macrophages, but the MEP cDNA is polyadenylated at a different site in the 3' non-coding region. Strong homology of MEP with human cathepsin L suggests that MEP is the mouse analogue of cathepsin L. Amino acid sequencing of the N-terminus of the secreted form of MEP indicates that, during secretion, the polypeptide is cleaved between amino acids 17 and 18. We have placed the MEP cDNA in a eukaryotic expression vector and demonstrated the production of the 39 kDa polypeptide form of mouse MEP in monkey CV-1 cells.
Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD 20892.
B R
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Troen
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Gottesman
D000595:Amino Acid Sequence; D001483:Base Sequence; D056668:Cathepsin L; D002403:Cathepsins; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases; D004247:DNA / Q000235:genetics*; D010450:Endopeptidases; D008969:Molecular Sequence Data; D014162:Transfection; D014169:Transformation, Bacterial
D004247:DNA; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; C534278:Ctsl protein, mouse