Cloning of cDNA for granzyme-like protein III, a novel serine proteinase from rat duodenum

We previously reported cloning of cDNAs which encode two granzyme-like serine proteinases (GLP I and GLP II) from rat duodenum. In this paper we present the cDNA sequence for a novel member of the granzyme-like protein family from rat duodenum, GLP III. The amino acid sequence deduced from the cDNA consists of 248 residues and shows 88.2% identity to GLP I and 50.6% identity to GLP II. Comparison of the amino acid sequence of GLP III with sequences of related proteinases reveals the location of the catalytic amino acid triad and enables the prediction of the substrate specificity. Despite close similarity to GLP I, GLP III is expected to demonstrate different substrate specificity due to a substitution of the Arg residue by Glu at the critical position. Northern blot analysis demonstrates that the GLP III transcript is present only in duodenum.