ZNRF2 is released from membranes by growth factors and with ZNRF1 regulates the Na+/K+ATPase

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    Abstract

    Here, we describe a phosphorylation-based reverse myristoyl switch for mammalian ZNRF2, and show that this E3 ubiquitin ligase and its sister protein ZNRF1 regulate the Na+/K+ pump (Na+/K+ATPase). N-myristoylation localizes ZNRF1 and ZNRF2 to intracellular membranes and enhances their activity. However, when ZNRF2 is phosphorylated in response to agonists including insulin and growth factors, it binds to 14-3-3 and is released into the cytosol. On membranes, ZNRF1 and ZNRF2 interact with the Na+/K+ATPase a1 subunit via their UBZ domains, while their RING domains interact with E2 proteins, predominantly Ubc13 that, together with Uev1a, mediates formation of Lys63-ubiquitin linkages. ZNRF1 and ZNRF2 can ubiquitylate the cytoplasmic loop encompassing the nucleotide-binding and phosphorylation regions of the Na+/K+ATPase a1 subunit. Ouabain, a Na+/K+ATPase inhibitor and therapeutic cardiac glycoside, decreases ZNRF1 protein levels, whereas knockdown of ZNRF2 inhibits the ouabain-induced decrease of cell surface and total Na+/K+ATPase a1 levels. Thus, ZNRF1 and ZNRF2 are new players in regulation of the ubiquitous Na+/K+ATPase that is tuned to changing demands in many physiological contexts.

    Original languageEnglish
    Pages (from-to)4662-4675
    Number of pages14
    JournalJournal of Cell Science
    Volume125
    Issue number19
    DOIs
    Publication statusPublished - 1 Oct 2012

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    Keywords

    • 14-3-3 Proteins
    • Amino Acid Sequence
    • Animals
    • Carrier Proteins
    • Cytoplasm
    • Gene Knockdown Techniques
    • HEK293 Cells
    • Humans
    • Intercellular Signaling Peptides and Proteins
    • Intracellular Membranes
    • Isotope Labeling
    • Mice
    • Molecular Sequence Data
    • Mutation
    • Ouabain
    • Phosphorylation
    • Phosphoserine
    • Protein Binding
    • Protein Structure, Tertiary
    • Protein Subunits
    • Protein Transport
    • Sodium-Potassium-Exchanging ATPase
    • Ubiquitin-Conjugating Enzymes
    • Ubiquitin-Protein Ligases
    • Ubiquitination

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