Fig. 3. HsOrc binding at oriP during the cell cycle. Different cell cycle phases were separated by centrifugal elutriation and five cell cycle fractions were subjected to ChIP (G1, 40 ml minute^-1; G1/S, 50 ml minute^-1; S, 60 ml minute^-1; S/G2, 80 ml minute^-1; G2/M, 90 ml minute^-1). Cross-linked chromatin of 1x10⁷ cells was used for each immunoprecipitation with antibodies directed against HsOrc3p (A), HsOrc6p (B) and HsOrc1p (C). Co-precipitated DNA was isolated and 1/50 thereof was used for each PCR. The mean values and standard deviations are calculated of four (A), and seven independent experiments (B,C).