Protein-coding gene in humans
Napsin-A is an aspartic proteinase that is encoded in humans by the NAPSA gene.[5] The name napsin comes from novel aspartic proteinase of the pepsin family.[6]
The activation peptide of an aspartic proteinase acts as an inhibitor of the active site. These peptide segments, or pro-parts, are deemed important for correct folding, targeting, and control of the activation of aspartic proteinase zymogens. The pronapsin A gene is expressed predominantly in lung and kidney. Its translation product is predicted to be a fully functional, glycosylated aspartic proteinase precursor containing an RGD motif and an additional 18 residues at its C-terminus.[5]
Utility
Detection of NAPSA gene expression can be used to distinguish adenocarcinomas from other forms of lung cancer.[7]