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| {{STRUCTURE_1hcn| PDB=1hcn | SCENE= }} | | {{STRUCTURE_1hcn| PDB=1hcn | SCENE= }} |
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| '''STRUCTURE OF HUMAN CHORIONIC GONADOTROPIN AT 2.6 ANGSTROMS RESOLUTION FROM MAD ANALYSIS OF THE SELENOMETHIONYL PROTEIN'''
| | ===STRUCTURE OF HUMAN CHORIONIC GONADOTROPIN AT 2.6 ANGSTROMS RESOLUTION FROM MAD ANALYSIS OF THE SELENOMETHIONYL PROTEIN=== |
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| ==Overview==
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| BACKGROUND: Human chorionic gonadotropin (hCG) is a placental hormone that stimulates secretion of the pregnancy-sustaining steroid progesterone. It is a member of a family of glycoprotein hormones that are disulfide-rich heterodimers, with a common alpha-chain and distinctive beta-chains specific to their particular G-protein linked receptors. RESULTS: We have produced recombinant hCG in mammalian cells as the selenomethionyl protein, and have determined its structure (after partial deglycosylation) at 2.6 A resolution from multiwavelength anomalous diffraction (MAD) measurements. Despite only limited sequence similarity (10% identity), the alpha- and beta-subunits of hCG have similar tertiary folds. Each subunit has a cystine-knot motif at its core of extended hairpin loops. There is a very extensive subunit interface featuring two inter-chain beta-sheets and a unique, disulfide-tethered 'arm' from the beta-subunit which 'embraces' the alpha-subunit. The carboxy-terminal peptide of the beta-subunit, which is rich in O-linked sugars, is disordered. CONCLUSIONS: Structural and sequence comparisons indicate an evolutionary homology, albeit remote, between the glycoprotein hormone chains and other cystine-knot proteins, notably platelet-derived growth factor. Segments of the alpha- and beta-chains that have been convincingly implicated in receptor binding by hCG are juxtaposed on one side of the molecule. A glycosylation site implicated in signal transduction but not in binding is also close to the presumed binding site suggesting a possible coupling between ligand binding and signaling. This study with selenomethionyl protein produced in mammalian cells extends the realm of MAD phasing.
| | The line below this paragraph, {{ABSTRACT_PUBMED_7922031}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 7922031 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_7922031}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Wu, H.]] | | [[Category: Wu, H.]] |
| [[Category: Hormone]] | | [[Category: Hormone]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 18:42:20 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 07:59:47 2008'' |
