<prompt> Which of the following is the donor of ADP-ribose for ADP-ribosylation reactions?Adenosine triphosphateAdenosine monophosphateNicotinamide adenine dinucleotideFlavin mononucleotide  <response>: ADP-ribosylation One of the histone post-translational modifications. NAD acts as the source of ADP-ribose. Eg : Mechanism of action of cholera toxin, diphtheria toxin and ricin 