Linked Life Data

9050234

Source:http://linkedlifedata.com/resource/pubmed/id/9050234

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 2
pubmed:dateCreated
1997-4-15
pubmed:abstractText
The electrogenic Na+:HCO3- cotransporter (symporter) is the major transporter for HCO3- reabsorption across the basolateral membrane of the renal proximal tubule and also contributes significantly to Na+ reabsorption. We expression-cloned the salamander renal electrogenic Na+:Bicarbonate Cotransporter (NBC) in Xenopus laevis oocytes. After injecting poly(A)+ RNA, fractionated poly(A)+ RNA or cRNA, we used microelectrodes to monitor membrane potential (Vm) and intracellular pH (pHi) All solutions contained ouabain to block the Na+/K+ pump (P-ATPase). After applying 1.5% CO2/10 mmol l-1 HCO3- (pH 7.5) and allowing pHi to stabilize from the CO2-induced acidification, we removed Na+. In native oocytes or water-injected controls, removing Na+ hyperpolarized the cell by -5 mV and had no effect on pHi. In oocytes injected with poly(A)+ RNA, removing Na+ transiently depolarized the cell by -10 mV and caused pHi to decrease; both effects were blocked by 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS) and required HCO3-. We enriched the signal by electrophoretic fractionation of the poly(A)+ RNA, and constructed a size-selected cDNA library in pSPORT1 using the optimal fraction. Screening the Ambystoma library yielded a single clone (aNBC). Expression was first obvious 3 days after injection of NBC cRNA. Adding CO2/HCO3- induced a large (> 50 mV) and rapid hyperpolarization, followed by a partial relaxation as pHi stabilized. Subsequent Na+ removal depolarized the cell by more than 40 mV and decreased pHi. aNBC is a full-length clone with a start Met and a poly(A)+ tail; it encodes a protein with 1025 amino acids and several putative membrane-spanning domains. aNBC is the first member of a new family of Na(+)-linked HCO3- transporters. We used aNBC to screen a rat kidney cDNA library, and identified a full-length cDNA clone (rNBC) that encodes a protein of 1035 amino acids. rNBC is 86% identical to aNBC and can be functionally expressed in oocytes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-0949
pubmed:author
pubmed:issnType
Print
pubmed:volume
200
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
263-8
pubmed:dateRevised
2010-12-3
pubmed:meshHeading
pubmed-meshheading:9050234-Ambystoma, pubmed-meshheading:9050234-Animals, pubmed-meshheading:9050234-Bicarbonates, pubmed-meshheading:9050234-Carrier Proteins, pubmed-meshheading:9050234-Cloning, Molecular, pubmed-meshheading:9050234-DNA, Complementary, pubmed-meshheading:9050234-Hydrogen-Ion Concentration, pubmed-meshheading:9050234-Kidney Tubules, Proximal, pubmed-meshheading:9050234-Membrane Potentials, pubmed-meshheading:9050234-Microinjections, pubmed-meshheading:9050234-Oocytes, pubmed-meshheading:9050234-RNA, Messenger, pubmed-meshheading:9050234-Rabbits, pubmed-meshheading:9050234-Recombinant Fusion Proteins, pubmed-meshheading:9050234-Sodium, pubmed-meshheading:9050234-Sodium-Bicarbonate Symporters, pubmed-meshheading:9050234-Structure-Activity Relationship, pubmed-meshheading:9050234-Xenopus laevis
pubmed:year
1997
pubmed:articleTitle
The renal electrogenic Na+:HCO-3 cotransporter.
pubmed:affiliation
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA. Boronwf@maspo3.mas.yale.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Review, Research Support, Non-U.S. Gov't