Effects of testosterone on protein synthesis in rat seminal vesicles analysed by two-dimensional gel electrophoresis.

Proteins synthesised by seminal vesicles of normal rats were labelled with [35S]methionine and were then separated using two-dimensional gel electrophoresis. Isoelectric focusing or nonequilibrium pH gradient electrophoresis were used in the first dimension followed by polyacrylamide gel electrophoresis under denaturing conditions. Using antiserum to total seminal vesicle secretion and running the immuno-precipitated proteins on two-dimensional gels, secretory proteins were identified and shown to be much more complex than previously thought. Proteins synthesised by seminal vesicles from rats castrated 1-2 weeks before were also labelled with [35S]methionine and separated on two-dimensional gels. Comparison of the two-dimensional protein maps from normal and castrated animals showed that a substantial number of proteins were differentially induced or repressed by testosterone. Of the secretory proteins, some were clearly regulated in a highly differential manner but others appeared to be unaffected by castration. The results are discussed in relation to previous measurements of mRNA sequence complexity and show that previous conclusions derived from using less sophisticated methods are oversimplifications of the response.