A full-length 1,209 bp cDNA encoding the human sex steroid-binding protein of plasma (SBP or SHBG) and testis (ABP) was constructed and expressed in BHK-21 cells. The sequence agrees with the published gene and protein sequences. The cells were found to secrete SBP following transfection and G418r selection. The recombinant protein binds 5α-dihydrotestosterone with a K d of 0.28 nM. It also binds testosterone and 17β-estradiol but not progesterone, estrone or cortisol revealing a steroid-binding specificity identical to that of human SBP, SDS-PAGE patterns are less complex than human SBP and show a monomeric molecular weight of about 43 kDa.
