What is the Difference Between PARP1 and PARP2?
🆚 Go to Comparative Table 🆚PARP1 and PARP2 are two enzymes involved in DNA damage repair and nucleosome remodeling. They share some similarities but also have distinct differences in their structure and function. Some key differences between PARP1 and PARP2 include:
- DNA binding affinity: PARP1 has high affinity for single-strand breaks in DNA and similar affinity for blunt ends, while PARP2 has high affinity for gaps and flap structures. PARP1 has the highest affinity for nick sites, followed by nucleotide break sites, and the lowest affinity for abasic/apyrimidinic (AP) sites. In contrast, PARP2 has similar affinity for nicked and AP sites and the lowest affinity for nucleotide break sites.
- Structural differences: The N-terminal domain of PARP2 does not contain zinc-finger motifs like PARP1 but instead has a highly basic DNA-binding domain (DBD) and nuclear and nucleolar localization signals. PARP2 is structurally different from PARP1, which may reflect differences in the DNA structures recognized by each enzyme.
- Poly(ADP-ribosyl)ation: PARP1 and PARP2 both catalyze poly(ADP-ribosyl)ation, but they have different efficiencies and preferences for substrates. PARP2 preferentially dimerizes on DNA breaks, while PARP1 is mostly monomeric on intact, AP sites, and gaps with minute dimer formation on nicked sites. PARP1 initiates the PAR chain, while the N-terminal region of PARP2 recognizes PAR chains, DNA, and RNA and performs secondary PARylation, including branching.
- Function in nucleosome remodeling: Both PARP1 and PARP2 play roles in maintaining genome stability and are involved in chromatin remodeling. However, PARP2 synthesizes shorter PAR chains than PARP1 and also inhibits PARP1-catalyzed PAR synthesis.
In summary, PARP1 and PARP2 share some common functions in DNA damage repair and nucleosome remodeling but have distinct structural and functional differences that allow them to recognize and interact with different DNA structures and perform specific roles in maintaining genome stability.
Comparative Table: PARP1 vs PARP2
PARP1 and PARP2 are two enzymes that are part of the PARP family, which plays a crucial role in normal DNA repair activities. Here is a table summarizing the differences between PARP1 and PARP2:
| Feature | PARP1 | PARP2 |
|---|---|---|
| Domain | Catalytic domain and N-terminal DNA binding domain | Catalytic domain, but lacks N-terminal DNA binding domain |
| DNA Binding | Binds efficiently to DNA single-strand breaks (SSB) | Binds less efficiently to DNA SSB, but recognizes gaps and flap structures |
| Finger Motifs | Contains 3 Zn-finger motifs and a WGR-domain | Has only an unstructured N-terminal domain and a WGR-domain |
These enzymes are involved in the repair of DNA damage and are essential for maintaining genome stability. PARP inhibitor drugs, which target PARP1, have been developed to treat certain types of cancer.
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