Quick Search:

uzh logo
Browse by:

Zurich Open Repository and Archive

Maintenance: Tuesday, 5.7.2016, 07:00-08:00

Maintenance work on ZORA and JDB on Tuesday, 5th July, 07h00-08h00. During this time there will be a brief unavailability for about 1 hour. Please be patient.

Köhler, K; Forster, I C; Stange, G; Biber, J; Murer, H (2002). Identification of functionally important sites in the first intracellular loop of the NaPi-IIa cotransporter. American Journal of Physiology: Renal Physiology, 282(4):F687-F696.

Full text not available from this repository.

View at publisher


Intrasequence comparison of the type IIa Na(+)-P(i) cotransport protein revealed two regions with high similarity in the first intracellular (ICL-1) and third extracellular (ECL-3) loops. Because the ECL-3 loop contains functionally important sites that have been identified by cysteine scanning, we applied this method to corresponding sites in the ICL-1 loop. The accessibility of novel cysteines by methanethiosulfonate reagents was assayed electrophysiologically. Mutants N199C and V202C were fully inhibited after methanethiosulfonate ethylammonium exposure, whereas other mutants showed marginal reductions in cotransport function. None showed significant functional loss after exposure to impermeant methanethiosulfonate ethyltrimethylammonium, which suggested a sidedness of Cys modification. Compared with the wild-type (WT), mutant A203C showed altered Na(+) leak kinetics, whereas N199C exhibited decreased apparent substrate affinities. To delineate the role of residue N199 in conferring substrate affinity, other mutations at this site were made. Only two mutants yielded significant (32)P(i) uptake and inward P(i)-induced currents with decreased P(i) affinity; for the others, P(i) application suppressed only the Na(+) leak. We suggest that ICL-1 and ECL-3 sites contribute to the transport pathway and that site N199 is implicated in defining the transport mode.


35 citations in Web of Science®
36 citations in Scopus®
Google Scholar™


Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
Dewey Decimal Classification:570 Life sciences; biology
Date:1 April 2002
Deposited On:11 Feb 2008 12:23
Last Modified:05 Apr 2016 12:18
Publisher:American Physiological Society
Publisher DOI:10.1152/ajprenal.00282.2001
PubMed ID:11880330

Users (please log in): suggest update or correction for this item

Repository Staff Only: item control page