1k4c

<table><tr><td colspan='2'>[[1k4c]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/"actinomyces_lividans"_krasil'nikov_et_al._1965 "actinomyces lividans" krasil'nikov et al. 1965] and [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. The February 2003 RCSB PDB [https://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''Potassium Channels'' by Shuchismita Dutta and David S. Goodsell is [https://dx.doi.org/10.2210/rcsb_pdb/mom_2003_2 10.2210/rcsb_pdb/mom_2003_2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K4C OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1K4C FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=DGA:DIACYL+GLYCEROL'>DGA</scene>, <scene name='pdbligand=F09:NONAN-1-OL'>F09</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene></td></tr>

[[https://www.uniprot.org/uniprot/KCSA_STRLI KCSA_STRLI]] Acts as a pH-gated potassium ion channel; changing the cytosolic pH from 7 to 4 opens the channel, although it is not clear if this is the physiological stimulus for channel opening. Monovalent cation preference is K(+) > Rb(+) > NH4(+) >> Na(+) > Li(+).<ref>PMID:7489706</ref>

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== Publication Abstract from PubMed ==

Ion transport proteins must remove an ion's hydration shell to coordinate the ion selectively on the basis of its size and charge. To discover how the K+ channel solves this fundamental aspect of ion conduction, we solved the structure of the KcsA K+ channel in complex with a monoclonal Fab antibody fragment at 2.0 A resolution. Here we show how the K+ channel displaces water molecules around an ion at its extracellular entryway, and how it holds a K+ ion in a square antiprism of water molecules in a cavity near its intracellular entryway. Carbonyl oxygen atoms within the selectivity filter form a very similar square antiprism around each K+ binding site, as if to mimic the waters of hydration. The selectivity filter changes its ion coordination structure in low K+ solutions. This structural change is crucial to the operation of the selectivity filter in the cellular context, where the K+ ion concentration near the selectivity filter varies in response to channel gating.

Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.,Zhou Y, Morais-Cabral JH, Kaufman A, MacKinnon R Nature. 2001 Nov 1;414(6859):43-8. PMID:11689936<ref>PMID:11689936</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1k4c" style="background-color:#fffaf0;"></div>

[[Category: Actinomyces lividans krasil'nikov et al. 1965]]

[[Category: Kaufman, A]]

[[Category: MacKinnon, R]]

[[Category: Morais-Cabral, J H]]

[[Category: Zhou, Y]]

[[Category: Protein-antibody fab complex]]