1sji
From Proteopedia
(New page: 200px<br /><applet load="1sji" size="450" color="white" frame="true" align="right" spinBox="true" caption="1sji, resolution 2.4Å" /> '''Comparing skeletal an...) |
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| - | [[Image:1sji.gif|left|200px]]<br /><applet load="1sji" size=" | + | [[Image:1sji.gif|left|200px]]<br /><applet load="1sji" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1sji, resolution 2.4Å" /> | caption="1sji, resolution 2.4Å" /> | ||
'''Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization'''<br /> | '''Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Calsequestrin, the major calcium storage protein of both cardiac and | + | Calsequestrin, the major calcium storage protein of both cardiac and skeletal muscle, binds and releases large numbers of Ca(2+) ions for each contraction and relaxation cycle. Here we show that two crystal structures for skeletal and cardiac calsequestrin are nearly superimposable not only for their subunits but also their front-to-front-type dimers. Ca(2+) binding curves were measured using atomic absorption spectroscopy. This method enables highly accurate measurements even for Ca(2+) bound to polymerized protein. The binding curves for both skeletal and cardiac calsequestrin were complex, with binding increases that correlated with protein dimerization, tetramerization, and oligomerization. The Ca(2+) binding capacities of skeletal and cardiac calsequestrin are directly compared for the first time, with approximately 80 Ca(2+) ions bound per skeletal calsequestrin and approximately 60 Ca(2+) ions per cardiac calsequestrin, as compared with net charges for these molecules of -80 and -69, respectively. Deleting the negatively charged and disordered C-terminal 27 amino acids of cardiac calsequestrin results in a 50% reduction of its calcium binding capacity and a loss of Ca(2+)-dependent tetramer formation. Based on the crystal structures of rabbit skeletal muscle calsequestrin and canine cardiac calsequestrin, Ca(2+) binding capacity data, and previous light-scattering data, a mechanism of Ca(2+) binding coupled with polymerization is proposed. |
==About this Structure== | ==About this Structure== | ||
| - | 1SJI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Canis_lupus_familiaris Canis lupus familiaris]. Full crystallographic information is available from [http:// | + | 1SJI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Canis_lupus_familiaris Canis lupus familiaris]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SJI OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Canis lupus familiaris]] | [[Category: Canis lupus familiaris]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Dunker, A | + | [[Category: Dunker, A K.]] |
[[Category: Fields, K.]] | [[Category: Fields, K.]] | ||
| - | [[Category: Kang, C | + | [[Category: Kang, C H.]] |
| - | [[Category: Kim, E | + | [[Category: Kim, E J.]] |
| - | [[Category: Park, H | + | [[Category: Park, H J.]] |
| - | [[Category: Park, I | + | [[Category: Park, I Y.]] |
[[Category: Youn, B.]] | [[Category: Youn, B.]] | ||
[[Category: calcium-binding]] | [[Category: calcium-binding]] | ||
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[[Category: muscle protein]] | [[Category: muscle protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:02:07 2008'' |
Revision as of 13:02, 21 February 2008
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Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization
Overview
Calsequestrin, the major calcium storage protein of both cardiac and skeletal muscle, binds and releases large numbers of Ca(2+) ions for each contraction and relaxation cycle. Here we show that two crystal structures for skeletal and cardiac calsequestrin are nearly superimposable not only for their subunits but also their front-to-front-type dimers. Ca(2+) binding curves were measured using atomic absorption spectroscopy. This method enables highly accurate measurements even for Ca(2+) bound to polymerized protein. The binding curves for both skeletal and cardiac calsequestrin were complex, with binding increases that correlated with protein dimerization, tetramerization, and oligomerization. The Ca(2+) binding capacities of skeletal and cardiac calsequestrin are directly compared for the first time, with approximately 80 Ca(2+) ions bound per skeletal calsequestrin and approximately 60 Ca(2+) ions per cardiac calsequestrin, as compared with net charges for these molecules of -80 and -69, respectively. Deleting the negatively charged and disordered C-terminal 27 amino acids of cardiac calsequestrin results in a 50% reduction of its calcium binding capacity and a loss of Ca(2+)-dependent tetramer formation. Based on the crystal structures of rabbit skeletal muscle calsequestrin and canine cardiac calsequestrin, Ca(2+) binding capacity data, and previous light-scattering data, a mechanism of Ca(2+) binding coupled with polymerization is proposed.
About this Structure
1SJI is a Single protein structure of sequence from Canis lupus familiaris. Full crystallographic information is available from OCA.
Reference
Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization., Park H, Park IY, Kim E, Youn B, Fields K, Dunker AK, Kang C, J Biol Chem. 2004 Apr 23;279(17):18026-33. Epub 2004 Feb 10. PMID:14871888
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