1hcn
From Proteopedia
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==Overview== | ==Overview== | ||
| - | BACKGROUND: Human chorionic gonadotropin (hCG) is a placental hormone that | + | 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. |
==About this Structure== | ==About this Structure== | ||
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Structure of human chorionic gonadotropin at 2.6 A resolution from MAD analysis of the selenomethionyl protein., Wu H, Lustbader JW, Liu Y, Canfield RE, Hendrickson WA, Structure. 1994 Jun 15;2(6):545-58. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7922031 7922031] | Structure of human chorionic gonadotropin at 2.6 A resolution from MAD analysis of the selenomethionyl protein., Wu H, Lustbader JW, Liu Y, Canfield RE, Hendrickson WA, Structure. 1994 Jun 15;2(6):545-58. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7922031 7922031] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Canfield, R | + | [[Category: Canfield, R E.]] |
| - | [[Category: Hendrickson, W | + | [[Category: Hendrickson, W A.]] |
[[Category: Liu, Y.]] | [[Category: Liu, Y.]] | ||
| - | [[Category: Lustbader, J | + | [[Category: Lustbader, J W.]] |
[[Category: Wu, H.]] | [[Category: Wu, H.]] | ||
[[Category: NAG]] | [[Category: NAG]] | ||
[[Category: hormone]] | [[Category: hormone]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:59:50 2008'' |
Revision as of 10:59, 21 February 2008
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STRUCTURE OF HUMAN CHORIONIC GONADOTROPIN AT 2.6 ANGSTROMS RESOLUTION FROM MAD ANALYSIS OF THE SELENOMETHIONYL PROTEIN
Overview
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.
About this Structure
1HCN is a Protein complex structure of sequences from [1] with as ligand. Full crystallographic information is available from OCA.
Reference
Structure of human chorionic gonadotropin at 2.6 A resolution from MAD analysis of the selenomethionyl protein., Wu H, Lustbader JW, Liu Y, Canfield RE, Hendrickson WA, Structure. 1994 Jun 15;2(6):545-58. PMID:7922031
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