The FXYD Gene Family of Small Ion Transport Regulators or Channels: cDNA Sequence, Protein Signature Sequence, and Expression

Sweadner, Kathleen J.; Rael, Efren

doi:10.1006/geno.2000.6274

Cited by 385 publications

(399 citation statements)

References 23 publications

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“…CHIF is a 67 amino acid, single-pass membrane protein, that is upregulated by aldosterone and corticosteroids in mammalian kidney and intestinal tracks, where it associates with the Na, K-ATPase to regulate Na + and K + homeostasis [21,22]. It is a member of the FXYD family proteins that are emerging as auxiliary, tissue-specific and physiological state-specific, subunits of the Na, K-ATPase [23]. We recently described the expression, purification and characterization of recombinant CHIF and other FXYD proteins [24].…”

Section: Membrane Proteins In Hydration-optimized Lipid Bilayer Samplesmentioning

confidence: 99%

Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

Marassi

Crowell

2003

Journal of Magnetic Resonance

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The preparation of oriented, hydration-optimized lipid bilayer samples, for NMR structure determination of membrane proteins, is described. The samples consist of planar phospholipid bilayers, containing membrane proteins, that are oriented on single pairs of glass slides, and are placed in the coil of the NMR probe with the bilayer plane perpendicular to the direction of the magnetic field. Lipid bilayers provide a medium that closely resembles the biological membrane, and sample orientation both preserves the intrinsic membrane-defined directional quality of membrane proteins, and provides the mechanism for resonance line narrowing. The hydrationoptimized samples overcome some of the difficulties associated with multi-dimensional, highresolution, solid-state NMR spectroscopy of membrane proteins. These samples have greater stability over the course of multidimensional NMR experiments, they have lower sample conductance for greater rf power efficiency, and enable greater rf coil filling factors to be obtained for improved experimental sensitivity. Sample preparation is illustrated for the membrane protein CHIF (channel inducing factor), a member of the FXYD family of ion transport regulators.

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Section: Membrane Proteins In Hydration-optimized Lipid Bilayer Samplesmentioning

confidence: 99%

Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

Marassi

Crowell

2003

Journal of Magnetic Resonance

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“…In this paper, the methods are described and illustrated with examples from the FXYD proteins, a family of tissue-specific and physiological-state-specific subunits of the Na,KATPase, that help to regulate the distribution of Na and K ion concentrations across animal cell membranes [17][18][19]. The FXYD protein sequences are highly conserved through evolution, and are characterized by a 35-amino acid FXYD homology domain, which includes the short signature motif PFXYD (Pro, Phe, X, Tyr, Asp) and the transmembrane domain (Fig.…”

Section: Introductionmentioning

confidence: 99%

NMR of membrane proteins in micelles and bilayers: The FXYD family proteins

Franzin

Gong

Thai

et al. 2007

Methods

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Determining the atomic resolution structures of membrane proteins is of particular interest in contemporary structural biology. Helical membrane proteins constitute one-third of the expressed proteins encoded in a genome, many drugs have membrane-bound proteins as their receptors, and mutations in membrane proteins result in human diseases. Although integral membrane proteins provide daunting technical challenges for all methods of protein structure determination, nuclear magnetic resonance (NMR) spectroscopy can be an extremely versatile and powerful method for determining their structures and characterizing their dynamics, in lipid environments that closely mimic the cell membranes. Once milligram amounts of isotopically labeled protein are expressed and purified, micelle samples can be prepared for solution NMR analysis, and lipid bilayer samples can be prepared for solid-state NMR analysis. The two approaches are complementary and can provide detailed structural and dynamic information. This paper describes the steps for membrane protein structure determination using solution and solid-state NMR. The methods for protein expression and purification, sample preparation and NMR experiments are described and illustrated with examples from the FXYD proteins, a family of regulatory subunits of the Na, KATPase.

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“…The FXYD protein family contains seven members that are characterized by one transmembrane domain and a signature sequence that contains the FXYD motif and 3 other conserved amino acids (7). FXYD2 or the ␥ subunit of Na,K-ATPase (8) was the first FXYD protein that was identified as a specific modulator of renal Na,K-ATPase (9 -13).…”

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confidence: 99%

Structural and Functional Interaction Sites between Na,K-ATPase and FXYD Proteins

Grosdidier

Crambert

et al. 2004

Journal of Biological Chemistry

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Several members of the FXYD protein family are tissue-specific regulators of Na,K-ATPase that produce distinct effects on its apparent K ؉ and Na ؉ affinity. Little is known about the interaction sites between the Na,KATPase ␣ subunit and FXYD proteins that mediate the efficient association and/or the functional effects of FXYD proteins. In this study, we have analyzed the role of the transmembrane segment TM9 of the Na,K-ATPase ␣ subunit in the structural and functional interaction with FXYD2, FXYD4, and FXYD7. Mutational analysis combined with expression in Xenopus oocytes reveals that Phe 956 , Glu 960 , Leu 964 , and Phe 967 in TM9 of the Na,K-ATPase ␣ subunit represent one face interacting with the three FXYD proteins. Leu 964 and Phe 967 contribute to the efficient association of FXYD proteins with the Na,K-ATPase ␣ subunit, whereas Phe 956 and Glu 960 are essential for the transmission of the functional effect of FXYD proteins on the apparent K ؉ affinity of Na,K-ATPase. The relative contribution of Phe 956 and Glu 960 to the K ؉ effect differs for different FXYD proteins, probably reflecting the intrinsic differences of FXYD proteins on the apparent K ؉ affinity of Na,K-ATPase. In contrast to the effect on the apparent K ؉ affinity, Phe 956 and Glu 960 are not involved in the effect of FXYD2 and FXYD4 on the apparent Na ؉ affinity of Na,K-ATPase. The mutational analysis is in good agreement with a docking model of the Na,K-ATPase/ FXYD7 complex, which also predicts the importance of Phe 956 , Glu 960 , Leu 964 , and Phe 967 in subunit interaction. In conclusion, by using mutational analysis and modeling, we show that TM9 of the Na,K-ATPase ␣ subunit exposes one face of the helix that interacts with FXYD proteins and contributes to the stable interaction with FXYD proteins, as well as mediating the effect of FXYD proteins on the apparent K ؉ affinity of Na,K-ATPase.

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The FXYD Gene Family of Small Ion Transport Regulators or Channels: cDNA Sequence, Protein Signature Sequence, and Expression

Cited by 385 publications

References 23 publications

Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

Hydration-optimized oriented phospholipid bilayer samples for solid-state NMR structural studies of membrane proteins

NMR of membrane proteins in micelles and bilayers: The FXYD family proteins

Structural and Functional Interaction Sites between Na,K-ATPase and FXYD Proteins

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