The new kallikrein-like gene, KLK-L2 - Molecular characterization, mapping, tissue expression, and hormonal regulation

Since in rodents the kallikreins are represented by a large multi-gene fami ly, the restriction of this family in humans to three genes is somewhat sur prising. In an effort to identify new human kallikrein genes, we examined a genomic area of about 300 kilobases on chromosome 19q13.3-q13.4, a region that contains most of the currently known kallikreins. By using the positio nal candidate approach, we were able to identify a new gene named KLK-L2 (f or kallikrein-like gene 2). Screening of human EST libraries allowed us to delineate the full genomic and cDNA structure of the new gene. KLK-L2 consi sts of 5 coding exons and 4 introns and has significant similarities to oth er members of the kallikrein multi-gene family. Homology studies suggest th at the protein is likely secreted. KLK-L2 is expressed mainly in breast, br ain, and testis and to a lesser extent in many other tissues. KLK-L2 is up- regulated by estrogens and progestins in the breast cancer cell line BT-474 .