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1j95

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KCSA potassium channel with TBA (tetrabutylammonium) and potassium

Structural highlights

1j95 is a 4 chain structure with sequence from Streptomyces lividans. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.8Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

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(+).^[1]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

Many voltage-dependent K+ channels open when the membrane is depolarized and then rapidly close by a process called inactivation. Neurons use inactivating K+ channels to modulate their firing frequency. In Shaker-type K+ channels, the inactivation gate, which is responsible for the closing of the channel, is formed by the channel's cytoplasmic amino terminus. Here we show that the central cavity and inner pore of the K+ channel form the receptor site for both the inactivation gate and small-molecule inhibitors. We propose that inactivation occurs by a sequential reaction in which the gate binds initially to the cytoplasmic channel surface and then enters the pore as an extended peptide. This mechanism accounts for the functional properties of K+ channel inactivation and indicates that the cavity may be the site of action for certain drugs that alter cation channel function.

Potassium channel receptor site for the inactivation gate and quaternary amine inhibitors.,Zhou M, Morais-Cabral JH, Mann S, MacKinnon R Nature. 2001 Jun 7;411(6838):657-61. PMID:11395760^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Schrempf H, Schmidt O, Kummerlen R, Hinnah S, Muller D, Betzler M, Steinkamp T, Wagner R. A prokaryotic potassium ion channel with two predicted transmembrane segments from Streptomyces lividans. EMBO J. 1995 Nov 1;14(21):5170-8. PMID:7489706
↑ Zhou M, Morais-Cabral JH, Mann S, MacKinnon R. Potassium channel receptor site for the inactivation gate and quaternary amine inhibitors. Nature. 2001 Jun 7;411(6838):657-61. PMID:11395760 doi:10.1038/35079500