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| - | [[Image:1x2w.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1x2w| PDB=1x2w | SCENE= }} | | {{STRUCTURE_1x2w| PDB=1x2w | SCENE= }} |
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| - | '''Crystal Structure of Apo-Habu IX-bp at pH 4.6'''
| + | ===Crystal Structure of Apo-Habu IX-bp at pH 4.6=== |
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| - | ==Overview==
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| - | Coagulation factor IX-binding protein, isolated from Trimeresurus flavoviridis (IX-bp), is a C-type lectin-like protein. It is an anticoagulant consisting of homologous subunits, A and B. Each subunit has a Ca(2+)-binding site with a unique affinity (K(d) values of 14muM and 130muM at pH 7.5). These binding characteristics are pH-dependent and, under acidic conditions, the Ca(2+) binding of the low-affinity site was reduced considerably. In order to identify which site has high affinity and to investigate the pH-dependent Ca(2+) release mechanism, we have determined the crystal structures of IX-bp at pH 6.5 and pH 4.6 (apo form), and compared the Ca(2+)-binding sites with each other and with those of the solved structures under alkaline conditions; pH 7.8 and pH 8.0 (complexed form). At pH 6.5, Glu43 in the Ca(2+)-binding site of subunit A displayed two conformations. One (minor) is that in the alkaline state, and the other (major) is that at pH 4.6. However, the corresponding Gln43 residue of subunit B is in only a single conformation, which is almost identical with that in the alkaline state. At pH 4.6, Glu43 of subunit A adopts a conformation similar to that of the major conformer observed at pH 6.5, while Gln43 of subunit B assumes a new conformation, and both Ca(2+) positions are occupied by water molecules. These results showed that Glu43 of subunit A is much more sensitive to protonation than Gln43 of subunit B, and the conformational change of Glu43 occurs around pH6.5, which may correspond to the step of Ca(2+) release.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_16165155}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 16165155 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_16165155}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Domain swapping]] | | [[Category: Domain swapping]] |
| | [[Category: Heterodimer]] | | [[Category: Heterodimer]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 14:27:43 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 11:28:11 2008'' |
Revision as of 08:28, 29 July 2008
Template:STRUCTURE 1x2w
Crystal Structure of Apo-Habu IX-bp at pH 4.6
Template:ABSTRACT PUBMED 16165155
About this Structure
1X2W is a Protein complex structure of sequences from Trimeresurus flavoviridis. Full crystallographic information is available from OCA.
Reference
pH-Dependent structural changes at Ca(2+)-binding sites of coagulation factor IX-binding protein., Suzuki N, Fujimoto Z, Morita T, Fukamizu A, Mizuno H, J Mol Biol. 2005 Oct 14;353(1):80-7. PMID:16165155
Page seeded by OCA on Tue Jul 29 11:28:11 2008
