View source for 2sas

[[Image:2sas.jpg|left|200px]]<br /><applet load="2sas" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="2sas, resolution 2.4&Aring;" />
'''STRUCTURE OF A SARCOPLASMIC CALCIUM-BINDING PROTEIN FROM AMPHIOXUS REFINED AT 2.4 ANGSTROMS RESOLUTION'''<br />

==Overview==
The three-dimensional structure of a sarcoplasmic Ca(2+)-binding protein from the protochordate amphioxus has been determined at 2.4 A resolution using multiple-isomorphous-replacement techniques. The refined model includes all 185 residues, three calcium ions, and one water molecule. The final crystallographic R-factor is 0.199. Bond lengths and bond angles in the molecules have root-mean-square deviations from ideal values of 0.015 A and 2.8 degrees, respectively. The overall structure is highly compact and globular with a predominantly hydrophobic core, unlike the extended dumbbell-shaped structures of calmodulin or troponin C. There are four distinct domains with the typical helix-loop-helix Ca(2+)-binding motif (EF hand). The conformation of the pair of EF hands in the N-terminal half of the protein is unusual due to the presence of an aspartate residue in the twelfth position of the first Ca(2+)-binding loop, rather than the usual glutamate. The C-terminal half of the molecule contains one Ca(2+)-binding domain with a novel helix-loop-helix conformation and one Ca(2+)-binding domain that is no longer functional because of amino acid changes. The overall structure is quite similar to a sarcoplasmic Ca(2+)-binding protein from sandworm, although there is only about 12% amino acid sequence identity between them. The similarity of the structures of these two proteins suggests that all sarcoplasmic Ca(2+)-binding proteins will have the same general conformation, even though there is very little conservation of primary structure among the proteins from various species.

==About this Structure==
2SAS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Branchiostoma_lanceolatum Branchiostoma lanceolatum] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2SAS OCA]. 

==Reference==
Structure of a sarcoplasmic calcium-binding protein from amphioxus refined at 2.4 A resolution., Cook WJ, Jeffrey LC, Cox JA, Vijay-Kumar S, J Mol Biol. 1993 Jan 20;229(2):461-71. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=8429557 8429557]
[[Category: Branchiostoma lanceolatum]]
[[Category: Single protein]]
[[Category: Babu, Y S.]]
[[Category: Cook, W J.]]
[[Category: Cox, J A.]]
[[Category: CA]]
[[Category: calcium-binding protein]]

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