Synthesis of acid phosphatase and other proteins by human prostatic tissue in vitro.

We have studied the synthesis of proteins by normal and hyperplastic human prostatic tissue incubated in vitro in the presence of [35S]methionine. The overall pattern of newly synthesized proteins was similar in individuals with an age ranging from 15 to 68 years. The pattern of labeled proteins was quite different from that of total proteins stained with Coomassie blue in two-dimensional polyacrylamide gels, since the major stained proteins was not labeled. Among the most heavily labeled proteins (about a dozen) were several spots representing charge isoforms with molecular weights ranging from 46 000 to 51 000, and these were the only proteins immunoprecipitated by a polyclonal antibody developed against purified acid phosphatase. The other heavily labeled proteins had molecular weights ranging from 26 000 to 72 000. These results show that tissue slices can be used to study the synthesis and processing of acid phosphatase, the major secretory product of the prostate, and of other unidentified proteins.