(A) (Left) Schematic illustrating NAD+ analog-sensitivity in PARP proteins. (Right) Residues in PARP-1 selected for mutation to glycine or alanine for discovery of gatekeeper residues.
(B) Chemical structures of the 11 NAD+ analogs used for screening for asPARP-1.
(C) Western blot for ADP-ribose from automodification reactions containing PARP-1 or PARP-1 mutants (L877A and I895A) and NAD+ or NAD+ analogs.
(D) Depiction of the spatial relationship between position 8 of the adenine ring in NAD+ and the gatekeeper residues.