Linked Life Data

19236841

Source:http://linkedlifedata.com/resource/pubmed/id/19236841

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2009-4-22
pubmed:abstractText
Homeostatic regulation of the plasma choline concentration depends on the effective functioning of a choline transporter in the kidney. However, the nature of the choline transport system in the kidney is poorly understood. In this study, we examined the molecular and functional characterization of choline uptake in the rat renal tubule epithelial cell line NRK-52E. Choline uptake was saturable and mediated by a single transport system, with an apparent Michaelis-Menten constant (K(m)) of 16.5 microM and a maximal velocity (V(max)) of 133.9 pmol/mg protein/min. The V(max) value of choline uptake was strongly enhanced in the absence of Na(+) without any change in K(m) values. The increase in choline uptake under Na(+)-free conditions was inhibited by Na(+)/H(+) exchanger (NHE) inhibitors. Choline uptake was inhibited by the choline uptake inhibitor hemicholinium-3 (HC-3) and organic cations, and was decreased by acidification of the extracellular medium and by intracellular alkalinization. Collapse of the plasma membrane H(+) electrochemical gradient by a protonophore inhibited choline uptake. NRK-52E cells mainly express mRNA for choline transporter-like proteins (CTL1 and CTL2), and NHE1 and NHE8. CTL1 protein was recognized in both plasma membrane and mitochondria. CTL2 protein was mainly expressed in mitochondria. The biochemical and pharmacological data indicated that CTL1 is functionally expressed in NRK-52E cells and is responsible for choline uptake. This choline transport system uses a directed H(+) gradient as a driving force, and its transport functions in co-operation with NHE8. Furthermore, the presence of CTL2 in mitochondria provides a potential site for the control of choline oxidation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
1096-0384
pubmed:author
pubmed:issnType
Electronic
pubmed:day
1
pubmed:volume
485
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
88-96
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Molecular and functional characterization of choline transporter in rat renal tubule epithelial NRK-52E cells.
pubmed:affiliation
Department of Pharmacology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, Japan.
pubmed:publicationType
Journal Article