View source for 9d18


==Ca2+ bound open-inactivated hSlo1 + beta2N-beta4 channel in detergent-conformation 2 of inactivating domain==
<StructureSection load='9d18' size='340' side='right'caption='[[9d18]], [[Resolution|resolution]] 2.88&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9d18]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9D18 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9D18 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 2.88&#8491;</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=CLR:CHOLESTEROL'>CLR</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=POV:(2S)-3-(HEXADECANOYLOXY)-2-[(9Z)-OCTADEC-9-ENOYLOXY]PROPYL+2-(TRIMETHYLAMMONIO)ETHYL+PHOSPHATE'>POV</scene></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=9d18 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9d18 OCA], [https://pdbe.org/9d18 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9d18 RCSB], [https://www.ebi.ac.uk/pdbsum/9d18 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9d18 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/KCMA1_HUMAN KCMA1_HUMAN] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
BK channels are large-conductance calcium (Ca(2+))-activated potassium channels crucial for neuronal excitability, muscle contraction, and neurotransmitter release. The pore-forming (alpha) subunits co-assemble with auxiliary (beta and gamma) subunits that modulate their function. Previous studies demonstrated that the N-termini of beta2-subunits can inactivate BK channels, but with no structural correlate. Here, we investigate BK beta2-subunit inactivation using cryo-electron microscopy, electrophysiology and molecular dynamics simulations. We find that the beta2 N-terminus occludes the pore only in the Ca(2+)-bound open state, via a ball-and-chain mechanism. The first three hydrophobic residues of beta2 are crucial for occlusion, while the remainder of the N-terminus remains flexible. Neither the closed channel conformation obtained in the absence of Ca(2+) nor an intermediate conformation found in the presence of Ca(2+) show density for the N-terminus of the beta2 subunit in their pore, likely due to narrower side access portals preventing their entry into the channel pore.

Ball-and-chain inactivation of a human large conductance calcium-activated potassium channel.,Agarwal S, Kim ED, Lee S, Simon A, Accardi A, Nimigean CM Nat Commun. 2025 Feb 19;16(1):1769. doi: 10.1038/s41467-025-56844-4. PMID:39971906<ref>PMID:39971906</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9d18" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Agarwal S]]
[[Category: Nimigean C]]