Linked Life Data

1652643

Source:http://linkedlifedata.com/resource/pubmed/id/1652643

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-9-27
pubmed:abstractText
Membrane fragments containing a high density of Na,K-ATPase can be noncovalently labeled with amphiphilic styryl dyes (e.g., RH 421). Phosphorylation of the Na,K-ATPase by ATP in the presence of Na+ and in the absence of K+ leads to a large increase of the fluorescence of RH 421 (up to 100%). In this paper evidence is presented that the styryl dye mainly responds to changes of the electric field strength in the membrane, resulting from charge movements during the pumping cycle: (i) The spectral characteristic of the ATP-induced dye response essentially agrees with the predictions for an electrochromic shift of the absorption peak. (ii) Adsorption of lipophilic anions to Na,K-ATPase membranes leads to an increase, adsorption of lipophilic cations to the decrease of dye fluorescence. These ions are known to bind to the hydrophobic interior of the membrane and to change the electric field strength in the boundary layer close to the interface. (iii) The fluorescence change that is normally observed upon phosphorylation by ATP is abolished at high concentrations of lipophilic ions. Lipophilic ions are thought to redistribute between the adsorption sites and water and to neutralize in this way the change of field strength caused by ion translocation in the pump protein. (iv) Changes of the fluorescence of RH 421 correlate with known electrogenic transitions in the pumping cycle, whereas transitions that are known to be electrically silent do not lead to fluorescence changes. The information obtained from experiments with amphiphilic styryl dyes is complementary to the results of electrophysiological investigations in which pump currents are measured as a function of transmembrane voltage. In particular, electrochromic dyes can be used for studying electrogenic processes in microsomal membrane preparations which are not amenable to electrophysiological techniques.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-2631
pubmed:author
pubmed:issnType
Print
pubmed:volume
121
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
141-61
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Charge translocation by the Na,K-pump: I. Kinetics of local field changes studied by time-resolved fluorescence measurements.
pubmed:affiliation
Department of Biology, University of Konstanz, Federal Republic of Germany.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't