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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-7200

Andriani, O; Chezzi, C; Murer, H; Forster, I C (2008). The leak mode of type II Na(+)-P(i) cotransporters. Channels, 2(5):346-357.

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Abstract

Na(+)-coupled phosphate cotransporters of the SLC34 gene family catalyze the movement of inorganic phosphate (P(i)) across epithelia by using the free energy of the downhill electrochemical Na(+) gradient across the luminal membrane. Electrogenic (NaPi- IIa/b) and electroneutral (NaPi-IIc) isoforms prefer divalent P(i) and show strict Na(+):P(i) stoichiometries of 3:1 and 2:1, respectively. For electrogenic cotransport, one charge is translocated per transport cycle. When NaPi-IIa or NaPi-IIb are expressed in Xenopus oocytes, application of the P(i) transport inhibitor phosphonoformic acid (PFA) blocks a leak current that is not detectable in the electroneutral isoform. In this review, we present the experimental evidence that this transport-independent leak originates from a Na(+)-dependent uniport carrier mode intrinsic to NaPi-IIa/b isoforms. Our findings, based on the characteristics of the PFA-inhibitable leak measured from wild type and mutant constructs, can be incorporated into an alternating access class model in which the leak and cotransport modes are mutually exclusive and share common kinetic partial reactions.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Integrative Human Physiology
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
DDC:570 Life sciences; biology
610 Medicine & health
Language:English
Date:20 September 2008
Deposited On:09 Dec 2008 10:25
Last Modified:14 Dec 2014 06:39
Publisher:Landes Bioscience
ISSN:1933-6950
Publisher DOI:10.4161/chan.2.5.6900
PubMed ID:18989094

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