The major excreted protein (MEP) of malignantly transformed mouse fibroblasts is the precursor to an acid proteinase with enzymic specificity similar to that of human cathepsin L. By cross-hybridization with a mouse MEP sequence, cDNA clones of the human form of MEP in an SV40 expression vector were isolated. A 1.6 kb cDNA showed 70% deduced amino acid sequence identity with mouse MEP. The deduced amino acid sequence of the cloned human MEP was the same, except for two amino acids, as the N-terminal sequence of mature human cathepsin L, thereby establishing that human MEP is human pro-(cathepsin L). Use of this human pro-(cathepsin L) cDNA clone allowed the detection of a 1.6-1.8 kb pro-(cathepsin L) mRNA in human cells which was not detected with a mouse pro-(cathepsin L) probe.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology