Quick Search:

uzh logo
Browse by:

Zurich Open Repository and Archive

Maintenance: Tuesday, July the 26th 2016, 07:00-10:00

ZORA's new graphical user interface will be relaunched (For further infos watch out slideshow ZORA: Neues Look & Feel). There will be short interrupts on ZORA Service between 07:00am and 10:00 am. Please be patient.

Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-48247

Ghezzi, C; Meinild, A K; Murer, H; Forster, I C (2011). Voltage- and substrate-dependent interactions between sites in putative re-entrant domains of a Na(+)-coupled phosphate cotransporter. Pflügers Archiv: European Journal of Physiology (Pflugers Archiv), 461(6):645-663.

[img]Published Version
PDF - Registered users only
View at publisher
Accepted Version


A common structural feature characterises sodium-coupled inorganic phosphate cotransporters of the SLC34 family (NaPi-IIa/b/c): a pair of inverted regions in the N- and C-terminal halves of the protein. These regions are hypothesised to contain re-entrant domains that associate to allow alternating access of the substrates from either side of the membrane. To investigate if these domains interact during the NaPi-II transport cycle, we introduced novel cysteines at three functionally important sites associated with the predicted re-entrant domains of the flounder NaPi-IIb for the purpose of fluorescent labelling and cross-linking. Single and double mutants were expressed in Xenopus oocytes and their function analysed using electrophysiological and real-time fluorometric assays. The substitution at the cytosolic end of the first re-entrant domain induced a large hyperpolarizing shift in the voltage dependence of steady-state and presteady-state kinetics, whereas the two substitutions at the external face were less critical. By using Cu-phenanthroline to induce disulfide bridge formation, we observed a loss of transport activity that depended on the presence of sodium in the incubation medium. This suggested that external sodium increased the probability of NaPi-IIb occupying a conformation that favours interaction between sites in the re-entrant domains. Furthermore, voltage-dependent fluorescence data supported the hypothesis that a localised interaction between the two domains occurs that depends on the membrane potential and substrate present: we found that the fluorescence intensity reported by a labelled cysteine in one domain was dependent on the side chain substituted at a functionally critical site in the opposed domain.


9 citations in Web of Science®
10 citations in Scopus®
Google Scholar™



68 downloads since deposited on 06 Jun 2011
20 downloads since 12 months

Detailed statistics

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

04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Deposited On:06 Jun 2011 12:21
Last Modified:05 Apr 2016 14:55
Additional Information:The original publication is available at www.springerlink.com
Publisher DOI:10.1007/s00424-011-0948-z
PubMed ID:21384128

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

Repository Staff Only: item control page