title: Structure-function relations of interactions between Na,K-ATPase, the gamma subunit, and corticosteroid hormone-induced factor.
abstract: Corticosteroid hormone-induced factor (CHIF) and the gamma subunit of the Na,K-ATPase (gamma) are two members of the FXYD family whose function has been elucidated recently. CHIF and gamma interact with the Na+ pump and alter its kinetic properties, in different ways, which appear to serve their specific physiological roles. Although functional interactions with the Na,K-ATPase have been clearly demonstrated, it is not known which domains and which residues interact with the alpha and/or beta subunits and affect the pump kinetics. The current study provides the first systematic analysis of structure-function relations of CHIF and gamma. It is demonstrated that the stability of detergent-solubilized complexes of CHIF and gamma with alpha and/or beta subunits is determined by the trans-membrane segments, especially three residues that may be involved in hydrophobic interactions. The transmembrane segments also determine the opposite effects of CHIF and gamma on the Na+ affinity of the pump, but the amino acids involved in this functional effect are different from those responsible for stable interactions with alpha.
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Moshit
authors.initials: M
authors.lastname: Lindzen
authors.forename: Roman
authors.initials: R
authors.lastname: Aizman
authors.forename: Yael
authors.initials: Y
authors.lastname: Lifshitz
authors.forename: Irina
authors.initials: I
authors.lastname: Lubarski
authors.forename: Steven J D
authors.initials: SJ
authors.lastname: Karlish
authors.forename: Haim
authors.initials: H
authors.lastname: Garty
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003902:Detergents; D004795:Enzyme Stability; D015870:Gene Expression; D005822:Genetic Vectors; D006367:HeLa Cells; D006801:Humans; D007163:Immunosorbent Techniques; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009840:Oligomycins / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D017354:Point Mutation; D051381:Rats; D011993:Recombinant Fusion Proteins; D012413:Rubidium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012995:Solubility; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D003902:Detergents; D008565:Membrane Proteins; D009840:Oligomycins; D011993:Recombinant Fusion Proteins; C422209:corticosteroid hormone-induced factor; D010042:Ouabain; D012964:Sodium; C416502:FXYD2 protein, human; C498817:Fxyd2 protein, rat; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium