Isolation and sequence of a human gene encoding a potent inhibitor of leukocyte proteases.

We report the isolation of the human gene encoding an inhibitor of neutrophil elastase and cathepsin G. We have sequenced the gene and a cDNA clone isolated from human parotid tissue. The protein encoded by this gene appears to contain two functional domains, one having a trypsin inhibitory site and the other an elastase inhibitory site. The two-domain structure of the protein is reflected in the organization of the gene, with each domain represented by a separate exon. We have also noted that the intervening sequence separating the trypsin-inhibitor-exon and the elastase-inhibitor-exon is flanked by eleven base-pair direct repeats, suggesting that this intron may have been generated by a transposition-type event.