|
rdf:type |
|
|
lifeskim:mentions |
|
|
pubmed:issue |
2
|
|
pubmed:dateCreated |
2000-2-18
|
|
pubmed:abstractText |
Inwardly rectifying K(+) currents are generated by a complex of four Kir (Kir1-6) subunits. Pore properties are conferred by the second transmembrane domain (M2) of each subunit. Using cadmium ions as a cysteine-interacting probe, we examined the accessibility of substituted cysteines in M2 of the Kir6.2 subunit of inwardly rectifying K(ATP) channels. The ability of Cd(2+) ions to inhibit channels was used as the estimate of accessibility. The distribution of Cd(2+) accessibility is consistent with an alpha-helical structure of M2. The apparent surface of reactivity is broad, and the most reactive residues correspond to the solvent-accessible residues in the bacterial KcsA channel crystal structure. In several mutants, single channel measurements indicated that inhibition occurred by a single transition from the open state to a zero-conductance state. Analysis of currents expressed from mixtures of control and L164C mutant subunits indicated that at least three cysteines are required for coordination of the Cd(2+) ion. Application of phosphatidylinositol 4,5-diphosphate to inside-out membrane patches stabilized the open state of all mutants and also reduced cadmium sensitivity. Moreover, the Cd(2+) sensitivity of several mutants was greatly reduced in the presence of inhibitory ATP concentrations. Taken together, these results are consistent with state-dependent accessibility of single Cd(2+) ions to coordination sites within a relatively narrow inner vestibule.
|
|
pubmed:grant |
|
|
pubmed:language |
eng
|
|
pubmed:journal |
|
|
pubmed:citationSubset |
IM
|
|
pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Adenosine Triphosphate,
http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Cadmium,
http://linkedlifedata.com/resource/pubmed/chemical/Cysteine,
http://linkedlifedata.com/resource/pubmed/chemical/Macromolecular Substances,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channel Blockers,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channels, Inwardly...,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/prokaryotic potassium channel
|
|
pubmed:status |
MEDLINE
|
|
pubmed:month |
Jan
|
|
pubmed:issn |
0021-9258
|
|
pubmed:author |
|
|
pubmed:issnType |
Print
|
|
pubmed:day |
14
|
|
pubmed:volume |
275
|
|
pubmed:owner |
NLM
|
|
pubmed:authorsComplete |
Y
|
|
pubmed:pagination |
1137-44
|
|
pubmed:dateRevised |
2007-11-14
|
|
pubmed:meshHeading |
pubmed-meshheading:10625656-Adenosine Triphosphate,
pubmed-meshheading:10625656-Amino Acid Sequence,
pubmed-meshheading:10625656-Amino Acid Substitution,
pubmed-meshheading:10625656-Animals,
pubmed-meshheading:10625656-Bacterial Proteins,
pubmed-meshheading:10625656-COS Cells,
pubmed-meshheading:10625656-Cadmium,
pubmed-meshheading:10625656-Cysteine,
pubmed-meshheading:10625656-Kinetics,
pubmed-meshheading:10625656-Macromolecular Substances,
pubmed-meshheading:10625656-Membrane Potentials,
pubmed-meshheading:10625656-Models, Molecular,
pubmed-meshheading:10625656-Molecular Sequence Data,
pubmed-meshheading:10625656-Patch-Clamp Techniques,
pubmed-meshheading:10625656-Potassium Channel Blockers,
pubmed-meshheading:10625656-Potassium Channels,
pubmed-meshheading:10625656-Potassium Channels, Inwardly Rectifying,
pubmed-meshheading:10625656-Protein Conformation,
pubmed-meshheading:10625656-Protein Structure, Quaternary,
pubmed-meshheading:10625656-Protein Structure, Secondary,
pubmed-meshheading:10625656-Recombinant Proteins,
pubmed-meshheading:10625656-Sequence Alignment,
pubmed-meshheading:10625656-Sequence Homology, Amino Acid
|
|
pubmed:year |
2000
|
|
pubmed:articleTitle |
Structure and dynamics of the pore of inwardly rectifying K(ATP) channels.
|
|
pubmed:affiliation |
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
|
|
pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|
