The cDNA-deduced primary structure of human sex hormone-binding globulin and location of its steroid-binding domain
Abstract
We have sequenced a cDNA for sex hormone-binding globulin (SHBG) isolated from a phage λgt 11 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 Δ6-[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.
- Publication:
-
FEBS Letters
- Pub Date:
- May 1987
- DOI:
- 10.1016/0014-5793(87)80121-7
- Bibcode:
- 1987FEBSL.215..100H
- Keywords:
-
- cDNA cloning;
- Amino acid sequence;
- Sex hormone-binding globulin;
- Steroid-binding domain;
- SHBG;
- sex hormone-binding globulin;
- also known as testosterone-estradiol-binding globulin (TeBG) and sex-steroid-binding protein (SBP);
- ABP;
- androgen-binding protein;
- Δ6-testosterone;
- 17β-hydroxyandrosta-4;
- 6-dien-3-one;
- SSPE;
- 150 mM NaCl/10 mM NaH2PO4H2O/1 mM EDTA (pH 7.4);
- SSC;
- 150 mM NaCl/15 mM sodium acetate (pH 7.4);
- Denhardt's solution;
- 0.02% Ficoll/0.02% polyvinylpyrrolidone/0.02% bovine serum albumin (Pentax;
- fraction V) in H2O (w/v)