Molecular cloning and expression of rat kallistatin gene

We have previously purified and cloned human kallistatin and rat kallikrein-binding protein (RKBP), which are tissue kallikrein inhibitors belonging to the serine proteinase inhibitor superfamily. In this study, we have cloned and sequenced the gene encoding rat kallistatin with Phe-Phe-Ser-Ala-Gln at positions P2-P3', which is identical to the reactive center of human kallistatin. Rat kallistatin is highly similar to human kallistatin, sharing 68% and 57% sequence identity at the cDNA and the amino acid levels. The rat kallistatin gene exists in a single copy and is located on chromosome 6. An SphI RFLP is found between SHR and WKY rats at or near the rat kallistatin gene locus. Two amino acid polymorphisms of the rat kallistatin gene between these two strains were found by sequence analysis. A candidate promoter in the 5'-flanking region (109 bp) of the rat kallistatin gene has been identified by reporter assays. The expression of rat kallistatin in the liver is growth-dependent and down-regulated during acute phase inflammation. Recombinant rat kallistatin produced in E. coli is able to bind to tissue kallikrein, and the interaction is inhibited by heparin. These characteristics define rat kallistatin as the counterpart of human kallistatin.