The cDNA-deduced primary structure of human sex hormone-binding globulin and location of its steroid-binding domain.
We have sequenced a cDNA for sex hormone-binding globulin (SHBG) isolated from a phage lambda gt11 human liver cDNA library. The library was screened with a radiolabeled rat androgen-binding protein (ABP) cDNA, and the abundance of SHBG cDNAs was 1 in 750,000 plaques examined. The largest human SHBG cDNA (1194 base-pairs) contained a reading frame for 381 amino acids. This comprised 8 amino acids of a signal peptide followed by 373 residues starting with the known NH2-terminal sequence of human SHBG, and ending with a termination codon. The predicted polypeptide Mr of SHBG is 40,509, and sites of attachment of one O-linked (residue 7) and two N-linked oligosaccharide (residues 351 and 367) chains were identified. Purified SHBG was photoaffinity-labeled with delta 6-[3H]testosterone and cleaved with trypsin. The labeled tryptic fragment was isolated by reverse-phase HPLC, and its NH2-terminal sequence was determined. The results suggest that a portion of the steroid-binding domain of SHBG is located between residue 296 and the 35 predominantly hydrophilic residues at the C-terminus of the protein.
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000032:analysis*; D004274:DNA, Recombinant / Q000032:analysis; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D006801:Humans; D008297:Male; D011485:Protein Binding; D012738:Sex Hormone-Binding Globulin / Q000235:genetics* / Q000378:metabolism
D004274:DNA, Recombinant; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin; D004247:DNA