The conserved PARP catalytic domain is indicated in yellow. The catalytic domain at the C terminus is conserved in all members and is required for NAD⁺ binding and PARylation activity. The zinc fingers domain in PARP1 is a DNA-binding site. The BRCA1 C terminus (BRCT), ankyrin repeat (ANK), sterile α-motif (SAM), and ubiquitin-interacting motif (UIM) domains are protein–protein interaction modules. The WGR, with conserved W, G and R residues, is a functionally unknown domain. The CCCH domain is a Cys–Cys–Cys–His zinc finger domain. The Macro and WWE (with conserved W, W and E residues) are ADP-ribose binding modules. The RNA recognition motif (RRM) is an RNA-binding motif. TM is a transmembrane domain.