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FASEB J. 2008 Mar;22(3):861-9. Epub 2007 Oct 10.

ADP-ribosylation at R125 gates the P2X7 ion channel by presenting a covalent ligand to its nucleotide binding site.

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Institute of Immunology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, D-20246 Hamburg, Germany.


ADP-ribosylation is a post-translational modification regulating protein function in which amino acid-specific ADP-ribosyltransferases (ARTs) transfer ADP-ribose from NAD onto specific target proteins. Attachment of the bulky ADP-ribose usually inactivates the target by sterically blocking its interaction with other proteins. P2X7, an ATP-gated ion channel with important roles in inflammation and cell death, in contrast, is activated by ADP-ribosylation. Here, we report the structural basis for this gating and present the first molecular model for the activation of a target protein by ADP-ribosylation. We demonstrate that the ecto-enzyme ART2.2 ADP-ribosylates P2X7 at arginine 125 in a prominent, cysteine-rich region at the interface of 2 receptor subunits. ADP-ribose shares an adenine-ribonucleotide moiety with ATP. Our results indicate that ADP-ribosylation of R125 positions this common chemical framework to fit into the nucleotide-binding site of P2X7 and thereby gates the channel.

[Indexed for MEDLINE]

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