Recognizes a protein of 45kDa, identified as SHBG. It functions as an androgen transport protein, but may also be involved in receptor-mediated processes. Each dimer binds one molecule of steroid. It is specific for 5-alpha-dihydrotestosterone, testosterone, and 17-beta-estradiol. SHBG regulates the plasma metabolic clearance rate of steroid hormones by controlling their plasma concentration. In testis, it is synthesized by the Sertoli cells, secreted into the lumen of the seminiferous tubule and transported to the epididymis.