Sequence and expression of the cDNA for MEP (major excreted protein), a transformation-regulated secreted cathepsin.

B. R. Troen, Susannah Gal, M. M. Gottesman

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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.

Original languageEnglish (US)
Pages (from-to)731-735
Number of pages5
JournalThe Biochemical journal
Issue number3
Publication statusPublished - Jan 1 1987


All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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