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. 2021 May 6;14:1827–1844. doi: 10.2147/JIR.S300679

Figure 1.

Figure 1

Scheme of poly (ADP-ribose) polymerase 1 (PARP-1) catalyzed poly (ADP-ribosylation) of the target protein. The PARP-1 catalytic domain attaches ADP-ribose polymers to proteins, catalyzing three different reactions – initiation (A), elongation (B) and branching (C). Initiation is the attachment of the first ADP-ribose monomer to the amino acid residue of the acceptor protein. Elongation, the attachment of further monomers, takes place through the formation of a (2ʹ-1ʹʹ) ribose-ribose glycosidic bond. Branching involves the creation of a ribose-ribose bond between ADP-ribose (2ʹʹ-1ʹʹʹ) units.