Rat prostatic acid phosphatase: androgenic control of isoelectric focusing patterns

Abstract

To further characterize the androgen dependence of prostatic acid phosphatase (AP), the isoelectric focusing patterns of enzyme activity have been examined for normal and castrated adult rats and for rats receiving androgen injections. Isoelectric focusing was performed in polyacrylamide gels over the pH range 4–8. Naphthyl phosphate was used as substrate for staining. For normal rats there was a single lysosomal band (isoelectric point (pI) = 7.35 ± 0.04), four closely migrating secretory bands (pI = 5.96–5.63), and an androgen-dependent band (pI = 6.37 ± 0.05) which as yet has not been identified as either lysosomal or secretory. Following castration the secretory bands decreased significantly in staining intensity, the androgen-dependent band disappeared, and two new lysosomal bands (pI's = 7.13 ± 0.03 and 7.00 ± 0.03) appeared. With androgen replacement the latter two bands disappeared, the androgen-dependent band reappeared, and the secretory bands increased in staining intensity but with the most anodic of the four appearing before the others. This suggests that it could be a precursor to the others. The isoelectric focusing patterns of AP activity appear to be a better method of assessing the androgen status of the prostate than are the previously used parameters, namely, enzyme specific activity, degree of inhibition by tartrate, and polyacrylamide gel electrophoretic pattern.