Two‐dimensional characterization of prostatic acid phosphatase, prostatic specific antigen and prostate binding protein in expressed prostatic fluid

Abstract

Specimens of pooled prostatic fluid, collected by rectal massage from men under 50 years of age with no apparent prostatic disorders, were subjected to two-dimensional gel electrophoresis to study the composition of its proteins. In a preliminary study, a total of 57 major protein groups were detected. In the present study, we attempted to identify, in the two-dimensional gels, those that are related to prostate-associated proteins, i.e., prostatic acid phosphatase (PAP), prostatic specific antigen (PSA), and prostate binding protein (PBP). Individual proteins were recognized by the procedure of Western Blot using specific antisera with peroxidase-antiperoxidase as the staining reagent. Each protein spot in the two-dimensional gel was expressed, along the abscissa, by its isoelectric point (pI) and, along the ordinate, by the molecular weight (MW). PAP consisted of a train of more than ten protein spots that occupied an area in the gel from pI 7.0, MW 45,000 to pI 6.0, MW 50,000. Four protein spots with a MW of 34,000 and a pI range of 8.2-8.8 were identified as PSA. PBP was observed as having three protein spots that were located at pI 5.6-6.6 with a single MW of 15,000. For PAP and PSA, additional protein spots with lower MWs also stained positively with the specific antisera, suggestive of the presence of degradative products of these proteins. Following the removal of the serum-related proteins by an extensive absorption with anti-human serum antibody by affinity chromatography, the prostatic fluid contained 27 major groups of non-serum proteins. These non-serum proteins in the prostatic fluid included PAP, PSA, PBP, and their related smaller molecular species. These results indicate that the prostatic fluid contains PAP, PSA, PBP and that their presence and the patterns of their distribution in the two-dimensional gels should be considered as the characteristic property of the prostatic secretions.

Identification of prostatic-secreted proteins in mice by mass spectrometric analysis and evaluation of lobe-specific and androgen-dependent mRNA expression

“…Prostatic secretory proteins have been studied in rats as well as in humans, especially from the viewpoint of androgen-dependent regulation of expression and to identify possible markers of prostate cancer. The major human prostatic-secreted proteins are PSA (prostate-specific antigen), PSP94, and prostatic acid phosphatase (Lee et al 1986). In rat, the composition of prostatic proteins is different; only PSP94 is common with the human case, and the production of each protein varies among lobes.…”

Expression of transmembrane serine protease TMPRSS2 in mouse and human tissues

“…Serine proteases, such as prostate-speci®c antigen (PSA) [1,2], human prostate-speci®c glandular kallikrein (hK2) [2,3] and prostase [4], are expressed mainly in a prostate-speci®c manner. A new member to this group of proteins is TMPRSS2, which was originally reported to be a small intestine-associated serine protease [5].…”

Identification of De Novo Synthesized and Relatively Older Proteins

“…In two-dimensional gel electrophoresis (2DGE) of tissues or body fluids, numerous protein gel spots can be identified, each representing the same protein identity (8–19). Often these numerous spots exist as charge variants and thus present as a train of spots horizontally adjacent to one another on the gel (8–19), each with similar molecular weights but with different isoelectric points (pI).…”

“…Often these numerous spots exist as charge variants and thus present as a train of spots horizontally adjacent to one another on the gel (8–19), each with similar molecular weights but with different isoelectric points (pI). This phenomenon has been observed for various proteins that have known relevance to disease, such as prostate-specific antigen (PSA) (18), heat shock proteins (15), fibrinogen (14), apolipoprotein A-1 (ApoA-1) (9–14), and many others. We hypothesized that the different protein isoforms in spot trains are related to different ages of proteins, and we hoped that experiments to further understand the nature of these proteins would improve the understanding of diseases that are related to an accumulation of aged proteins.…”