Glandular kallikreins of the cotton-top tamarin: Molecular cloning of the gene encoding the tissue kallikrein

The glandular kallikrein family is composed of structurally related serine proteases, Studies show that the mouse family encompasses at least 14 highl y conserved functional genes, but of these only the tissue kallikarein has a human ortholog, In man, the tissue kallikrein display high sequence simil arity with prostate specific antigen and human glandular kallikrein 2, sugg esting that they evolved after the separation of primates and rodents, A ph ylogenetic study of the genes encoding glandular kallikreins in species evo lutionarily located between rodents and man may reveal interesting details on how the gene family evolved, which in turn could yield information about the function of the proteins, Therefore, we have initiated a study of the glandular kallikreins of the cotton-top tamarin (Saguinus oedipus), a New W orld Monkey. Here, we report the cloning and nucleotide sequence of one of these, the tissue kallikrein gene. The gene of 4.4 kb is composed of five e xons, and the structure is 90% similar to that of the orthologous human gen e. It gives rise to a polypeptide of 261 amino acids, including a signal pe ptide of 17 residues, a pro-piece of 7 residues, and the mature protein of 237 residues,vith an estimated molecular mass of 26.3 kD, The similarity, t o the human prostate specific antigen and human glandular kallikrein 2 gene s is 73% and 72%, respectively, including introns and flanking regions, The lower similarity to these genes compared with the human tissue kallikrein gene indicates that they, or a progenitor to them, arose in primates prior to the separation of New and Old World monkeys. Genomic Southern blots also show that the cotton-top tamarin genome encompasses at least one more glan dular kallikrein gene.