The Rat Androgen Receptor: Primary Structure, Autoregulation of its Messenger Ribonucleic Acid, and Immunocytochemical Localization of the Receptor Protein

A composite androgen receptor DNA sequence 4,181 base pairs in length was determined from three cDNA clones isolated from a rat epididymal bacteriophage lambda gt11 library. An open reading frame of 902 amino acids encodes a protein of 98,227 mol wt. Structural domains characteristic of the steroid receptor family include an amino-terminal region with five repeated amino acid motifs, a central DNA-binding domain homologous with other steroid receptors, and a carboxyl-terminal steroid-binding region. A receptor cDNA probe used in Northern blot analysis hybridized with a predominant 10-kilobase androgen receptor mRNA in male reproductive tissues of the rat. Autoregulation of androgen receptor mRNA was indicated in rat ventral prostate by an increase in the level of 10-kilobase mRNA after castration and suppression of receptor mRNA upon androgen restimulation. A 15 amino acid peptide with sequence derived from the deduced androgen receptor sequence was synthesized and used as immunogen in raising receptor antibodies in rabbits. Antisera reacted with high titer against the synthetic peptide by enzyme-linked immunosorbent assay and against the native 3Hdihydrotestosterone-labeled androgen receptor as evidenced by an increase in receptor sedimentation rate determined by sucrose gradient centrifugation. Immunocytochemical staining localized the androgen receptor to epithelial cell nuclei in rat ventral prostate.