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Metabolite Card

Note

Adenosine diphosphate ribose is a molecule formed into poly(ADP-ribose) or PAR chains by the enzyme poly ADP ribose polymerase or PARP. PARP is found in every cell nucleus. Its main role is to detect and signal single-strand DNA breaks (SSB) to the enzymatic machinery involved in the SSB repair. PARP activation is an immediate cellular response to metabolic, chemical, or radiation-induced DNA SSB damage. Once PARP detects a SSB, it binds to the DNA, and, after a structural change, begins the synthesis of a poly (ADP-ribose) chain (PAR) as a signal for the other DNA-repairing enzymes such as DNA ligase III (LigIII), DNA polymerase beta, and scaffolding proteins such as X-ray cross-complementing gene 1 (XRCC1). After repairing, the PAR chains are degraded via PAR glycohydrolase (PARG). ADP-ribose binds to and activates the TRPM2 ion channel. Adenosine diphosphate ribose is an intermediate in NAD metabolism. The enzyme NAD(P)+ nucleosidase [EC:3.2.2.6] catalyzes the production of this metabolite from nicotinamide adenine dinucleotide phosphate. This reaction is irreversible and occurs in the cytosol.