Figure 4. CST disrupts the interaction between MCM and CDT1.

(A) Yeast-two-hybrid analysis was used to analyze the interaction between CDT1 and MCM. Yeast diploids grown on DDO medium were selected on TDO medium or QDO medium for binding and expression. Colony growth was monitored 3–4 d after plating and incubation. Data are representative of three independent biological experiments. (B) Co-IP of lysates from HEK 293T cells expressing Flag-MCM subunits and CDT1-HA with or without expression of CST subunits (+CS: CTC1 and STN1; +CST: CTC1, STN1, and TEN1), as indicated. Relative CDT1-HA band intensity was compared between no CST or CST expression, as indicated below the gel (see the Material and Methods section). Data are representative of three independent biological experiments for +CST. Replicate experiment is shown in Fig S4. (C) Model of how CST binding to MCM could block CDT1 binding to MCM.