Department of Biochemistry, University of Georgia, Athens.
The human U937 cell line, a promonocyte-like leukemic line, has been shown to synthesize neutrophil elastase (Senior, R. M. et al. (1982) J. Clin. Invest. 69, 384-393). We have constructed a lambda gt11 cDNA library using RNA from this cell line and isolated a clone encoding part of the protein sequence of neutrophil elastase. Nucleotide sequencing indicates the clone encodes residues 108-243 (standard chymotrypsinogen numbering) of the enzyme, plus a hitherto unsuspected 20 residue-C-terminal extension of unusual structure. Comparison of the nucleotide and amino-acid sequence of elastase with the recently reported sequence of medullasin, a proteinase isolated from bone marrow, suggests they are identical.