Human prostate-specific glandular kallikrein is expressed as an active and an inactive protein

• Published in: Clinical chemistry (Baltimore, Md.) Md.), 1997-02, Vol.43 (2), p.279-284
• Main Authors: Herrala, Annakaisa, Kurkela, Riitta, Porvari, Katja, Isomaki, Ritva, Henttu, Pirkko, Vihko, Pirkko
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; DNA - chemistry; DNA - isolation & purification; Gene Expression; Genotype; Humans; Kallikreins - genetics; Kallikreins - metabolism; Leukocytes - chemistry; Male; Medical sciences; Nephrology. Urinary tract diseases; Polymerase Chain Reaction; Polymorphism, Genetic; Prostate - chemistry; Prostatic Hyperplasia - metabolism; Prostatic Neoplasms - chemistry; Recombinant Proteins; Sequence Analysis, DNA; Tissue Kallikreins; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/43.2.279

A polymorphism in the human prostate-specific glandular kallikrein (hKLK2) gene was described by direct sequencing (by PCR) of genomic DNAs isolated from prostatic cancer tissue, benign prostatic hyperplasia tissue, and blood leukocyte specimens. Results showed two forms of human prostate-specific glandular kallikrein protein (hK2), a consequence of a change from C to T at base 792 in the hK2 coding region. Producing the two forms as recombinant proteins in insect cells demonstrated that Arg226-hK2 (CC genotype) is an active protein and Trp226-hK2 (TT genotype) is inactive. Polymorphism studies of 36 patients with prostatic diseases identified only 1 with the TT genotype. The same kind of polymorphism was not detected in the human prostate-specific antigen (hKLK3) gene. Arg226-hK2 possessed only trypsin-like enzyme activity, whereas recombinant human prostate-specific antigen (hPSA) had only chymotrypsin-like activity. Monoclonal and polyclonal antibodies raised against hPSA purified from seminal plasma detected both active and inactive hK2. Thus, because inactive as well as stable hK2 protein may be present, a lack of trypsin-like activity in hPSA standards is not enough to confirm that the materials are free of hK2 contamination.