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| ==Calcium-calmodulin complexed with the calmodulin binding domain from a small conductance potassium channel splice variant== | | ==Calcium-calmodulin complexed with the calmodulin binding domain from a small conductance potassium channel splice variant== |
| <StructureSection load='4j9y' size='340' side='right' caption='[[4j9y]], [[Resolution|resolution]] 1.51Å' scene=''> | | <StructureSection load='4j9y' size='340' side='right'caption='[[4j9y]], [[Resolution|resolution]] 1.51Å' scene=''> |
| == Structural highlights == | | == Structural highlights == |
| <table><tr><td colspan='2'>[[4j9y]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4J9Y OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4J9Y FirstGlance]. <br> | | <table><tr><td colspan='2'>[[4j9y]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4J9Y OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4J9Y FirstGlance]. <br> |
| </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.51Å</td></tr> |
| <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1g4y|1g4y]], [[4g27|4g27]], [[4g28|4g28]], [[3sjq|3sjq]], [[4j9z|4j9z]]</td></tr> | | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> |
| <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">Kcnn2 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10116 Rattus norvegicus]), Calm1, Calm, Cam, Cam1, Calm2, Cam2, Camb, Calm3, Cam3, Camc ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10116 Rattus norvegicus])</td></tr> | | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4j9y FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4j9y OCA], [https://pdbe.org/4j9y PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4j9y RCSB], [https://www.ebi.ac.uk/pdbsum/4j9y PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4j9y ProSAT]</span></td></tr> |
| <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4j9y FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4j9y OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4j9y RCSB], [http://www.ebi.ac.uk/pdbsum/4j9y PDBsum]</span></td></tr> | |
| </table> | | </table> |
| == Function == | | == Function == |
| [[http://www.uniprot.org/uniprot/KCNN2_RAT KCNN2_RAT]] Forms a voltage-independent potassium channel activated by intracellular calcium. Activation is followed by membrane hyperpolarization. Thought to regulate neuronal excitability by contributing to the slow component of synaptic afterhyperpolarization. The channel is blocked by apamin. | | [https://www.uniprot.org/uniprot/KCNN2_RAT KCNN2_RAT] Forms a voltage-independent potassium channel activated by intracellular calcium. Activation is followed by membrane hyperpolarization. Thought to regulate neuronal excitability by contributing to the slow component of synaptic afterhyperpolarization. The channel is blocked by apamin. |
| <div style="background-color:#fffaf0;">
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| == Publication Abstract from PubMed ==
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| Most proteins, such as ion channels, form well-organized 3D structures to carry out their specific functions. A typical voltage-gated potassium channel subunit has six transmembrane segments (S1-S6) to form the voltage-sensing domain and the pore domain. Conformational changes of these domains result in opening of the channel pore. Intrinsically disordered (ID) proteins/peptides are considered equally important for the protein functions. However, it is difficult to explore the structural features underlying the functions of ID proteins/peptides by conventional methods, such as X-ray crystallography, because of the flexibility of their secondary structures. Unlike voltage-gated potassium channels, families of small- and intermediate-conductance Ca(2+)-activated potassium (SK/IK) channels with important roles in regulating membrane excitability are activated exclusively by Ca(2+)-bound calmodulin (CaM). Upon binding of Ca(2+) to CaM, a 2 x 2 structure forms between CaM and the CaM-binding domain. A channel fragment that connects S6 and the CaM-binding domain is not visible in the protein crystal structure, suggesting that this fragment is an ID fragment. Here we show that the conformation of the ID fragment in SK channels becomes readily identifiable in the presence of NS309, the most potent compound that potentiates the channel activities. This well-defined conformation of the ID fragment, stabilized by NS309, increases the channel open probability at a given Ca(2+) concentration. Our results demonstrate that the ID fragment, itself a target for drugs modulating SK channel activities, plays a unique role in coupling Ca(2+) sensing by CaM and mechanical opening of SK channels.
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| Unstructured to structured transition of an intrinsically disordered protein peptide in coupling Ca2+-sensing and SK channel activation.,Zhang M, Pascal JM, Zhang JF Proc Natl Acad Sci U S A. 2013 Mar 19;110(12):4828-33. doi:, 10.1073/pnas.1220253110. Epub 2013 Mar 4. PMID:23487779<ref>PMID:23487779</ref>
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| From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| </div>
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| ==See Also== | | ==See Also== |
| *[[Calmodulin|Calmodulin]] | | *[[Calmodulin 3D structures|Calmodulin 3D structures]] |
| *[[Potassium Channel|Potassium Channel]] | | *[[Potassium channel 3D structures|Potassium channel 3D structures]] |
| == References ==
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| <references/>
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| __TOC__ | | __TOC__ |
| </StructureSection> | | </StructureSection> |
| | [[Category: Large Structures]] |
| [[Category: Rattus norvegicus]] | | [[Category: Rattus norvegicus]] |
| [[Category: Pascal, J M]] | | [[Category: Pascal JM]] |
| [[Category: Zhang, J F]] | | [[Category: Zhang J-F]] |
| [[Category: Zhang, M]] | | [[Category: Zhang M]] |
| [[Category: Calcium binding]]
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| [[Category: Ef hand]]
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| [[Category: Sk2a channel fragment]]
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| [[Category: Transport protein-calcium binding complex]]
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