Linked Life Data

10727708

Source:http://linkedlifedata.com/resource/pubmed/id/10727708

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2000-5-25
pubmed:abstractText
We have examined the sensitivity of human and rat homo-oligomeric rho(1) GABA receptors to variations in extracellular pH (pH(o)) using the whole-cell patch clamp technique. The GABA-induced conductance mediated by the rat rho(1) receptor (rho(1)-R) decreased with a decrease in pH(o) between 9.0 to 5.4. Below pH(o) 7.4 the effect of protons on the GABA-induced conductance was apparently competitive, but above pH(o) 7.4 the inhibitory effect of extracellular protons was almost independent on the GABA concentration. Titration of the GABA-induced conductance at 3 microM GABA revealed two protonation sites on rat rho(1)-R with pKa 6.4 and pKa 8.2. At 10 microM GABA the low pKa (6.4) was shifted to a clearly lower value (5.6), but the high pKa was only slightly decreased (from 8.2 to 7.9). Zn(2+) ions were capable of relieving the proton inhibition at low pH(o) indicating that Zn(2+) interacts with the low pKa site. Unlike the rat rho(1)-R, the human rho(1)-R was sensitive only to changes in pH(o) at acidic levels. Proton inhibition of human rho(1)-R was apparently competitive, as observed on rat-rho(1) at acidic pH(o). Titration of the human rho(1)-R gave a single H(+) binding site with a pKa of 6.3, similar to the value for the low pKa on rat rho(1)-R. The pKa value of human rho(1)-R was not dependent on the GABA concentration. A chimeric receptor, consisting of the N-terminal part of the rat rho(1)-R and C-terminal part of the human rho(1)-R, displayed pH(o) sensitivity similar to that observed for rat rho(1)-R. This indicates that the high pKa of rat rho(1)-R is attributable to the 11 amino acid differences between the rat and human rho(1)-R extracellular domains.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0028-3908
pubmed:author
pubmed:issnType
Print
pubmed:day
3
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
977-89
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed-meshheading:10727708-Amino Acid Sequence, pubmed-meshheading:10727708-Animals, pubmed-meshheading:10727708-Binding Sites, pubmed-meshheading:10727708-Cell Line, pubmed-meshheading:10727708-Electric Conductivity, pubmed-meshheading:10727708-Extracellular Space, pubmed-meshheading:10727708-GABA Antagonists, pubmed-meshheading:10727708-Humans, pubmed-meshheading:10727708-Hydrogen-Ion Concentration, pubmed-meshheading:10727708-Membrane Potentials, pubmed-meshheading:10727708-Molecular Sequence Data, pubmed-meshheading:10727708-Patch-Clamp Techniques, pubmed-meshheading:10727708-Protons, pubmed-meshheading:10727708-Rats, pubmed-meshheading:10727708-Receptors, GABA, pubmed-meshheading:10727708-Receptors, GABA-A, pubmed-meshheading:10727708-Receptors, GABA-B, pubmed-meshheading:10727708-Recombinant Fusion Proteins, pubmed-meshheading:10727708-Zinc
pubmed:year
2000
pubmed:articleTitle
Different sensitivities of human and rat rho(1) GABA receptors to extracellular pH.
pubmed:affiliation
Department of Biosciences, Division of Animal Physiology, P.O. Box 17, FIN-00014 University of Helsinki, Finland.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't