Structure/function analyses of human sex hormone‐binding globulin by site‐directed mutagenesis

FEBS Letters

Warmels-Rodenhiser, S.¹  Hammond, G.L.¹  Bocchinfuso, W.P.¹ 

[1] Departments of Obstetrics and Gynecology, Biochemistry, and Oncology, and MRC Group in Fetal and Neonatal Health and Development, University of Western Ontario, London, Ont. N6A 4L6, Canada

关键词: Sex hormone-binding globulin;    Androgen-binding protein;    Steroid-binding domain;    Epitope;    Site-directed mutagenesis;    hSHBG;    human sex hormone-binding globulin;    rABP;    rat androgen-binding protein;    CHO;    chinese barnster ovary;    DCC;    dextran-coated charcoal;    DHT;    5α-dihydrotestosterone;    PAGE;    polyacrylamide gel electrophoresis;   

DOI  :  10.1016/0014-5793(92)81253-I

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Human sex hormone-binding globulin (hSHBG) and rat androgen-binding protein (rABP) exhibit distinct affinities for sex-steroids. We therefore constructed and expressed a hSHBG/rABP hybrid cDNA encoding the N-terminal portion of hSHBG (205 residues) and the C-terminal portion of rABP (168 residues). The resulting chimera displayed similar steroid-binding characteristics as hSHBG and was recognised by a monoclonal antibody (S1B5) for hSHBG. We then created substitutions at Ser-133, His-136 and Met-139. The Asp-133 and Gln-136 mutants bound steroids in the same way as normal hSHBG while the steroid-binding affinity of Trp-139 was reduced. All three mutants cross-reacted similarly in a hSHBG radioimmunoassay, but Gln-136 was recognised poorly by the S1B5 antibody. These data imply that residues involved in steroid-binding are located within the N-terminal half of hSHBG and include Met-139, and that the S1B5 epitope is located in this region.

【 授权许可】

Unknown