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| - | [[Image:2pq3.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_2pq3| PDB=2pq3 | SCENE= }} | | {{STRUCTURE_2pq3| PDB=2pq3 | SCENE= }} |
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| - | '''N-Terminal Calmodulin Zn-Trapped Intermediate'''
| + | ===N-Terminal Calmodulin Zn-Trapped Intermediate=== |
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| - | ==Overview==
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| - | Calmodulin (CaM) is a 16.8-kDa calcium-binding protein involved in calcium-signal transduction. It is the canonical member of the EF-hand family of proteins, which are characterized by a helix-loop-helix calcium-binding motif. CaM is composed of N- and C-terminal globular domains (N-CaM and C-CaM), and within each domain there are two EF-hand motifs. Upon binding calcium, CaM undergoes a significant, global conformational change involving reorientation of the four helix bundles in each of its two domains. This conformational change upon ion binding is a key component of the signal transduction and regulatory roles of CaM, yet the precise nature of this transition is still unclear. Here, we present a 1.3-A structure of zinc-bound N-terminal calmodulin (N-CaM) solved by single-wavelength anomalous diffraction phasing of a selenomethionyl N-CaM. Our zinc-bound N-CaM structure differs from previously reported CaM structures and resembles calcium-free apo-calmodulin (apo-CaM), despite the zinc binding to both EF-hand motifs. Structural comparison with calcium-free apo-CaM, calcium-loaded CaM, and a cross-linked calcium-loaded CaM suggests that our zinc-bound N-CaM reveals an intermediate step in the initiation of metal ion binding at the first EF-hand motif. Our data also suggest that metal ion coordination by two key residues in the first metal-binding site represents an initial step in the conformational transition induced by metal binding. This is followed by reordering of the N-terminal region of the helix exiting from this first binding loop. This conformational switch should be incorporated into models of either stepwise conformational transition or flexible, dynamic energetic state sampling-based transition.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17942116}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17942116 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_17942116}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: N-cam]] | | [[Category: N-cam]] |
| | [[Category: N-terminal calmodulin]] | | [[Category: N-terminal calmodulin]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 13:36:34 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 11:27:15 2008'' |
Revision as of 08:27, 28 July 2008
Template:STRUCTURE 2pq3
N-Terminal Calmodulin Zn-Trapped Intermediate
Template:ABSTRACT PUBMED 17942116
About this Structure
2PQ3 is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
A 1.3-A structure of zinc-bound N-terminal domain of calmodulin elucidates potential early ion-binding step., Warren JT, Guo Q, Tang WJ, J Mol Biol. 2007 Nov 23;374(2):517-27. Epub 2007 Sep 21. PMID:17942116
Page seeded by OCA on Mon Jul 28 11:27:15 2008
