Abstract: Molecular characteristics of the androgen receptor (AR) from 6-months old albino rat testes were studied. Using radioligand methods, gel filtration on Toyopearl HW-55F column and analyses of specific testicular cytosol 5-a-dihydrotestosterone binding in Scatchard and Hill plots it was shown that functional androgen receptor complexes (ARC's) are dimers exhibiting positive cooperativity during hormone ligand binding. The cooperative properties of AR were stable not only at 4°C (Hill coefficient = 2.11) but also at physiological temperature of 36°C (Hill coefficient = 1.95).
Presence of Na2MoO4Ч2H2O (10 mM) and/or dilution of cytosols reduced Hill coefficient to 1.03. Addition of morning (but not afternoon) blood sera microquantities (1:20) to monomerized AR preparations resulted in the AR dimerization and restoration of their positive cooperative properties for hormone binding. The effect of morning sera persisted through their pretreatment (15-h at 4°C) with suspensions of 2.5% dextran coated charcoal. Sera from 28-months old rats lacked AR dimerizing activity.
Reference: Popoff E.H., Study of androgen receptor cooperative characteristics, Biomeditsinskaya khimiya, 2004, vol: