1lhw
CRYSTAL STRUCTURE OF THE N-TERMINAL LG-DOMAIN OF SHBG IN COMPLEX WITH 2-METHOXYESTRADIOL
Structural highlights
FunctionSHBG_HUMAN Functions as an androgen transport protein, but may also be involved in receptor mediated processes. Each dimer binds one molecule of steroid. Specific for 5-alpha-dihydrotestosterone, testosterone, and 17-beta-estradiol. Regulates the plasma metabolic clearance rate of steroid hormones by controlling their plasma concentration. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIn a crystal structure of the amino-terminal laminin G-like domain of human sex hormone-binding globulin (SHBG), the biologically active estrogen metabolite, 2-methoxyestradiol (2-MeOE2), binds in the same orientation as estradiol. The high affinity of SHBG for 2-MeOE2 relies primarily on hydrogen bonding between the hydroxyl at C-3 of 2-MeOE2 and Asp(65) and an interaction between the methoxy group at C-2 and the amido group of Asn(82). Accommodation of the 2-MeOE2 methoxy group causes an outward displacement of residues Ser(128)-Pro(130), which appears to disorder and displace the loop region (Leu(131)-His(136)) that covers the steroid-binding site. This could influence the binding kinetics of 2-MeOE2 and/or facilitate ligand-dependent interactions between SHBG and other proteins. Occupancy of a zinc-binding site reduces the affinity of SHBG for 2-MeOE2 and estradiol in the same way. The higher affinity of SHBG for estradiol derivatives with a halogen atom at C-2 is due to either enhanced hydrogen bonding between the hydroxyl at C-3 and Asp(65) (2-fluoroestradiol) or accommodation of the functional group at C-2 (2-bromoestradiol), rather than an interaction with Asn(82). By contrast, the low affinity of SHBG for 2-hydroxyestradiol can be attributed to intra-molecular hydrogen bonding between the hydroxyls in the aromatic steroid ring A, which generates a steric clash with the amido group of Asn(82). Understanding how C-2 derivatives of estradiol interact with SHBG could facilitate the design of biologically active synthetic estrogens. Crystal structure of human sex hormone-binding globulin in complex with 2-methoxyestradiol reveals the molecular basis for high affinity interactions with C-2 derivatives of estradiol.,Avvakumov GV, Grishkovskaya I, Muller YA, Hammond GL J Biol Chem. 2002 Nov 22;277(47):45219-25. Epub 2002 Sep 11. PMID:12228253[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||||
