Human Nedd4 interacts with the human epithelial Na+ channel: WW3 but not WW1 binds to Na+-channel subunits.

The epithelial Na(+) channel (ENaC) regulates Na(+) absorption in epithelial tissues including the lung, colon and sweat gland, and in the distal nephrons of the kidney. When Na(+)-channel function is disrupted, salt and water homoeostasis is affected. The cytoplasmic regions of the Na(+)-channel subunits provide binding sites for other proteins ...
to interact with and potentially regulate Na(+)-channel activity. Previously we showed that a proline-rich region of the alpha subunit of the Na(+) channel bound to a protein of 116 kDa from human lung cells. Here we report the identification of this protein as human Nedd4, a ubiquitin-protein ligase that binds to the Na(+)-channel subunits via its WW domains. Further, we show that WW domains 2, 3 and 4 of human Nedd4 bind to the alpha, beta and gamma Na(+)-channel subunits but not to a mutated beta subunit. In addition, when co-expressed in Xenopus oocytes, human Nedd4 down-regulates Na(+)-channel activity.
Mesh Terms:
Amino Acid Motifs, Amino Acid Sequence, Animals, Base Sequence, Binding Sites, COS Cells, Calcium-Binding Proteins, Cloning, Molecular, Dogs, Endosomal Sorting Complexes Required for Transport, Epithelial Sodium Channel, Humans, Ligases, Molecular Sequence Data, Oocytes, RNA, Messenger, Recombinant Proteins, Sequence Homology, Amino Acid, Sodium Channels, Ubiquitin-Protein Ligases, Xenopus, src Homology Domains
Biochem. J.
Date: Feb. 01, 2000
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