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| | {{STRUCTURE_2hf5| PDB=2hf5 | SCENE= }} | | {{STRUCTURE_2hf5| PDB=2hf5 | SCENE= }} |
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| - | '''The structure and function of a novel two-site calcium-binding fragment of calmodulin'''
| + | ===The structure and function of a novel two-site calcium-binding fragment of calmodulin=== |
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| - | ==Overview==
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| - | Calmodulin (CaM) is an EF-hand protein composed of two calcium (Ca(2+))-binding EF-hand motifs in its N-domain (EF-1 and EF-2) and two in its C-domain (EF-3 and EF-4). In this study, we examined the structure, dynamics, and Ca(2+)-binding properties of a fragment of CaM containing only EF-2 and EF-3 and the intervening linker sequence (CaM2/3). Based on NMR spectroscopic analyses, Ca(2+)-free CaM2/3 is predominantly unfolded, but upon binding Ca(2+), adopts a monomeric structure composed of two EF-hand motifs bridged by a short antiparallel beta-sheet. Despite having an "even-odd" pairing of EF-hands, the tertiary structure of CaM2/3 is similar to both the "odd-even" paired N- and C-domains of Ca(2+)-ligated CaM, with the conformationally flexible linker sequence adopting the role of an inter-EF-hand loop. However, unlike either CaM domain, CaM2/3 exhibits stepwise Ca(2+) binding with a K (d1) = 30 +/- 5 microM to EF-3, and a K (d2) > 1000 microM to EF-2. Binding of the first equivalent of Ca(2+) induces the cooperative folding of CaM2/3. In the case of native CaM, stacking interactions between four conserved aromatic residues help to hold the first and fourth helices of each EF-hand domain together, while the loop between EF-hands covalently tethers the second and third helices. In contrast, these aromatic residues lie along the second and third helices of CaM2/3, and thus are positioned adjacent to the loop between its "even-odd" paired EF-hands. This nonnative hydrophobic core packing may contribute to the weak Ca(2+) affinity exhibited by EF-2 in the context of CaM2/3.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17473011}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17473011 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_17473011}} |
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| | ==About this Structure== | | ==About this Structure== |
| - | 2HF5 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HF5 OCA]. | + | 2HF5 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HF5 OCA]. |
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| | ==Reference== | | ==Reference== |
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| | [[Category: Ef-hand]] | | [[Category: Ef-hand]] |
| | [[Category: Hlh]] | | [[Category: Hlh]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 06:13:08 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 16:35:24 2008'' |
Revision as of 13:35, 29 July 2008
Template:STRUCTURE 2hf5
The structure and function of a novel two-site calcium-binding fragment of calmodulin
Template:ABSTRACT PUBMED 17473011
About this Structure
2HF5 is a Single protein structure of sequence from Homo sapiens. Full experimental information is available from OCA.
Reference
Calcium-induced folding of a fragment of calmodulin composed of EF-hands 2 and 3., Lakowski TM, Lee GM, Okon M, Reid RE, McIntosh LP, Protein Sci. 2007 Jun;16(6):1119-32. Epub 2007 May 1. PMID:17473011
Page seeded by OCA on Tue Jul 29 16:35:24 2008
