Genetic study of pancreatic proteinase in mice (Mus musculus): genetic variants of trypsin and chymotrypsin.

Three to five isozymes of pancreatic proteinase exist in mice, and they have been designated as bands I, II, III, IV, and V. Identification experiments of these isozymes were carried out in this study; bands I, IV, and V are trypsin, and bands II and III are chymotrypsin. Therefore, it is concluded that Prt-1, controlling band V, is a locus for trypsin and Prt-2, controllong bands II and III, is a locus for chymotrypsin. In addition, a new locus, Prt-3, has been found. At this locus the two allelic genes, Prt-3a and Prt-3b, control the low and high tryptic activities of band IV, respectively. Prt-3 is present only in the strain Mol-A. Linkage experimentation has shown that Prt-1 is closely linked to Prt-3.