Phosphorylation and nuclear processing of the androgen receptor.

Although transformed androgen receptor (AR) complexes derived from cytosol and nuclear AR complexes have been shown to bind with high affinity to nuclei and DNA, we have shown that the binding characteristics of the two receptor populations to rat ventral prostate nuclei are different. To account for these differences, we investigated the possibility that the two receptor populations differed in phosphorylation status. Significantly, an anti-phosphotyrosine antibody immunoprecipitated androgen binding from the nuclear AR preparation but not from the transformed cytosolic receptor preparation. These studies suggest that (i) further processing of the AR complex takes place after it has become transformed, and (ii) phosphorylation of the complex is one modification which occurs during the processing of the nuclear receptor.