OVEREXPRESSION OF A HUMAN PROSTATE-SPECIFIC GLANDULAR KALLIKREIN, HK2, IN ESCHERICHIA-COLI AND GENERATION OF ANTIBODIES

The genomic and the cDNA clones of human glandular kallikrein (hK2), a member of the kallikrein family, have been isolated; however, the hK2 protein has not yet been identified and characterized. The deduced se quence of hK2 is highly homologous to prostate specific antigen (PSA), a widely accepted prognostic indicator of prostate carcinoma. Also, h K2 mRNA, like PSA mRNA, is exclusively expressed in prostatic epitheli a. These two properties make hK2 a potentially useful marker for study ing prostate cancer. In this paper, we describe for the first time the overexpression of the entire hK2 protein (pre-pro hK2:pphK2) in the E , coli system. Our system yields high levels of authentic pphK2 (as de termined by partial amino acid Sequence analysis) comprising about 40% of total cellular protein. pphK2 was purified to near homogeneity by preparative SDS/PAGE and used to generate anti-pphK2 antibodies in rab bits. The antibodies recognize the recombinant hK2 protein and a major band of similar to 34 kDa in seminal fluid.