Figure 1

Comparison of domains for Orc1-5 and Cdc6 from S. cerevisiae. Orc1, Orc4, Orc5, and Cdc6 each contain an AAA+ domain as part of a larger ORC/Cdc6 domain (orange) [75]. Orc2 and Orc3 are predicted to share this domain structure [19], but have a greater degree of sequence divergence. Motifs within the AAA+ domain include Walker A (WA), Walker B (WB), Sensor-1 (S1) and Sensor-2 (S2). The carboxy-terminal region of ORC/Cdc6 is predicted to contain a winged-helix domain (WH), involved in DNA binding. Orc1 contains an additional BAH (bromo-adjacent homology) domain (pink), which interacts with the Sir1 protein and is involved in epigenetic silencing. Orc1 and Orc2 have regions of disorder (yellow); a DNA-binding AT-hook motif (here PRKRGRPRK) is identified in S. cerevisiae Orc2, and several of these have also been identified in disordered regions in S. pombe Orc4. The number of amino acids for each protein is indicated at the right.