Figure 5

Comparison of BRCT domains. (a) CLUSTAL-W alignment of the PARP-1 BRCT domain (PARP), the second BRCT domain of XRCC1 (X1BRCTb), and the first BRCA1 BRCT domain (BRCA1). Residues contributing to the BRCA1 phospho-serine binding site are underlined and in red font; dual repeat interacting residues in the tandem BRCA1 BRCT domains are underlined and in green font, and XRCC1 homodimer interface residues are underlined and in cyan font (adapted from [31]). (b) Stereo view of a superposition of the structure of the sixth BRCT domain of TopBP1 (magenta) and PARP-1 BRCT (cyan). (c) Close-up stereo view of the superposition of the BRCA1 BRCT domain phosphoserine binding site (magenta) and the homologous region from the PARP-1 BRCT domain (cyan). Residues interacting with the phosphoserine (orange) in the BRCA1 BRCT domain (magenta), as well as structurally homologous residues from the PARP-1 BRCT domain (cyan) are shown in stick representation.