ADP-ribosylation transfers an ADP-ribose group from NAD+ to a target, commonly a protein, with release of nicotinamide. It is a post-translational modification distinct from phosphorylation: the transferred chemical group is different, as are the enzymes that add or remove it. A modification can alter a target's activity or interactions without changing its encoded protein sequence. [ref]
ADP-ribosylation of membrane proteins catalyzed by cholera toxin: basis of the activation of adenylate cyclase by D. M. Gill and others. 1978, abstract and pp. 3050–3054: toxin-dependent protein modification and adenylate-cyclase activity
The cholera toxin experiments linked NAD+-dependent modification of a membrane-associated protein to persistent activation of adenylyl cyclase. They provide a concrete example of how a covalent chemical change can amplify a cellular signal. Other ADP-ribosylation systems have different targets and outcomes, so the chemical name alone does not specify one biological response.
New to topics? Read the docs here!