Characterization of the calf uterine androgen receptor and its activation to the deoxyribonucleic acid-binding state.
The androgen receptor (AR) from calf uterine cytosol has been studied in terms of steroid-binding affinity, hormone dissociation kinetics, and DNA-cellulose-binding capacity. The binding affinity for three androgens, analyzed under conditions where binding to progesterone receptor did not occur, decreased in the order: methyltrienolone greater than 5 alpha-dihydrotestosterone greater than testosterone. Activation of the receptor to the DNA-binding state involved the following changes of the receptor: decrease in dissociation rate for the steroid, disaggregation of the receptor, and increase in affinity for DNA. Dissociation studies with methyltrienolone and 5 alpha-dihydrotestosterone revealed that the AR can exist in two affinity states which differ 13- to 30-fold in their affinity for the steroid. Molybdate (10-20 mM) prevented the formation of the high affinity state. The high affinity state receptor was formed in the absence of molybdate or after ammonium sulfate precipitation (0-40% saturation) of the molybdate-stabilized low affinity state receptor. During formation of the high affinity state, the sedimentation coefficient of the receptor in low ionic strength buffer decreased from 8-9S to 4.5S, indicating receptor disaggregation. DNA-cellulose binding capacity increased from 3 to 65% upon formation of the high affinity state. The DNA-binding form could be eluted from DNA-cellulose at 0.14 M NaCl. After elution the DNA-binding form maintained its sedimentation coefficient of 4.5S and chromatographed as a protein with a Stokes radius of 44 A. From these results it can be concluded that the activated, DNA-binding form of the AR in calf uterus is a protein with a molecular mass of approximately 85,000, which acquires a higher affinity for the ligand upon its formation.
D000645:Ammonium Sulfate; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002482:Cellulose / Q000031:analogs & derivatives / Q000378:metabolism; D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002627:Chemistry, Physical; D003600:Cytosol / Q000378:metabolism; D004247:DNA / Q000031:analogs & derivatives / Q000378:metabolism*; D013196:Dihydrotestosterone / Q000378:metabolism; D004963:Estrenes / Q000378:metabolism; D005260:Female; D007700:Kinetics; D015741:Metribolone; D008970:Molecular Weight; D008982:Molybdenum / Q000494:pharmacology; D011944:Receptors, Androgen / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism; D014222:Triamcinolone Acetonide / Q000378:metabolism; D014599:Uterus / Q000378:metabolism*
C033190:DNA-cellulose; D004963:Estrenes; D011944:Receptors, Androgen; D013196:Dihydrotestosterone; C044659:molybdate; D015741:Metribolone; D013739:Testosterone; D008982:Molybdenum; D002482:Cellulose; D004247:DNA; D014222:Triamcinolone Acetonide; D000645:Ammonium Sulfate