Abstract
The FXYD family proteins are auxiliary subunits of the Na,K-ATPase, expressed primarily in tissues that specialize in fluid or solute transport, or that are electrically excitable. These proteins range in size from about 60 to 160 amino acid residues, and share a core homology of 35 amino acid residues in and around a single transmembrane segment. Despite their relatively small sizes, they are all encoded by genes with six to nine small exons. We show that the helical secondary structures of three FXYD family members, FXYD1, FXYD3, and FXYD4, determined in micelles by NMR spectroscopy, reflect the structures of their corresponding genes. The coincidence of helical regions, and connecting segments, with the positions of intron-exon junctions in the genes, support the hypothesis that the FXYD proteins may have been assembled from discrete structural modules through exon shuffling.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Exons
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Gene Components
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Gene Rearrangement
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Humans
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Intracellular Signaling Peptides and Proteins / chemistry
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Intracellular Signaling Peptides and Proteins / genetics
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Mice
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Micelles
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Neoplasm Proteins / chemistry
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Neoplasm Proteins / genetics
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Nuclear Magnetic Resonance, Biomolecular
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Phosphoproteins / chemistry
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Phosphoproteins / genetics
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Potassium Channels / chemistry
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Potassium Channels / genetics
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Protein Structure, Secondary
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Rats
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Sodium Dodecyl Sulfate
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Sodium-Potassium-Exchanging ATPase / chemistry*
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Sodium-Potassium-Exchanging ATPase / genetics*
Substances
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FXYD3 protein, human
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Fxyd4 protein, rat
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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Micelles
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Neoplasm Proteins
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Phosphoproteins
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Potassium Channels
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phospholemman
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Sodium Dodecyl Sulfate
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Sodium-Potassium-Exchanging ATPase