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FXYD proteins: New regulators of Na,K-ATPase

English title FXYD proteins: New regulators of Na,K-ATPase
Applicant Geering Käthi
Number 107513
Funding scheme Project funding
Research institution Département de Pharmacologie & Toxicologie Faculté de Biologie et de Médecine Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Cellular Biology, Cytology
Start/End 01.04.2005 - 31.03.2008
Approved amount 479'000.00
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All Disciplines (2)

Cellular Biology, Cytology
Molecular Biology

Keywords (5)

FXYD proteins; ion transport regulation; protein-protein interaction; Na; K-ATPase

Lay Summary (English)

Lay summary
The family of FXYD proteins contains 7 members, the functions of which are still poorly understood. We have identified FXYD1 or phospholemman, FXYD2 or the gamma subunit of Na,K-ATPase, FXYD4 or CHIF and FXYD7 as tissue- and isozyme-specific regulators of Na,K-ATPase, an ubiquitous plasma membrane protein that is responsible for the maintenance of the characteristic Na+ and K+ gradients between the intra- and extracellular milieu of animal cells. Significantly, each of these auxiliary subunits modifies the transport properties of Na,K-ATPase in a distinct way adapted to the physiological needs of the tissue in which they are expressed.These results highlight the complexity of the regulation of Na+ and K+ handling by Na,K-ATPase which is necessary to assure appropriate tissue functions such as renal Na+ reabsorption, muscle contractility and neuronal excitability. Moreover, mutation of a conserved glycine residue in FXYD2 has been linked to cases of human hypomagnesemia indicating that perturbations in the regulation of Na,K-ATPase by FXYD proteins may be critically involved in pathophysiological states.
General objectives:The project aims to A) characterize surfaces of interaction between the transmembrane (TM) domain of the alpha subunit of Na,K-ATPase and the TM domain of FXYD proteins which permit stable interactions and transmit the functional effect of FXYD proteins and B) elucidate structural and functional properties of members of the FXYD protein family which have so far not been studied.
Specific aims and experimental approaches:
1) Elucidation of structural and functional interaction sites between Na,K-ATPase and FXYD proteins
Interaction sites will be studied by site-directed mutagenesis, expression in Xenopus oocytes, co-immunoprecipitations, electrophysiological measurements and protein modeling. Moreover, the role of oligomerization of FXYD proteins in the association with Na,K-ATPase will be assessed by co-immunoprecipitation of epitope-tagged FXYD proteins and by 2-D Blue-Native electrophoresis.
2)FXYD7: Regulation of ER exit and intracellular transport
A C-terminalvaline residue was shown to control rapid ER exit of FXYD7. To establish the role of the C-terminal valine residue, we will apply a yeast two hybrid screen and pull-down experiments to identify proteins interacting with the C-terminus of FXYD7.
3) FXYD3: Characterization ofstructural and functional properties
We will analyze thebiosynthesis, processing, membrane topology, tissue distribution and functional properties of FXYD3 and assess its role in cell proliferationand/or apoptosis.
Expected value of the proposed project:Dysregulation of Na,K-ATPase through a defective production or function of tissue-specific regulators has been correlated with various disorders, including cardiovascular, neurological, renal and metabolic diseases. The proposed research project will improve the understanding of a novel regulatory mechanism of Na,K-ATPase and serve as a starting point to better understand its role in pathophysiological states.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
64793 Protein-protein interactions in the regulation of Na,K-ATPase expression and function 01.10.2001 Project funding