Fig. 2
CUL4ADET1-COP1 interacts with Sox2 and regulates its stability. a Network view of E3–Sox2 interactions (left panel) and the E3 hierarchical tree for Sox2 (right panel). UbiBrowser was employed to explore the E3 ligases for Sox2. The representative predicted E3 ligases surround Sox2. The node colors and characters reflect the E3 type. The edge width, the node size, and the edge shade are corrected with the confidence score. The predicted E3s and their position in the E3 family hierarchical tree was presented. In this tree, texts in each circle (just like “U”, “D” and “SO”) represent the E3 family. The number in the bracket following each E3 family represents the number of corresponding predicted E3–Sox2 interaction. b NPCs cell lysates were subjected to immunoprecipitation with control IgG or anti-Sox2 antibodies and detected CUL4A, COP1, DET1, DDB1, Roc1, and Sox2 protein levels. c The lysates of HEK293T cells transfected with indicated constructs were subjected to immunoprecipitation with anti-Myc or Histidine tag-specific affinity resin (agarose beads). The immunoprecipitates or the eluates were then blotted. d Overview of the structures of COP1 wild type and different truncates. HEK293T cells were co-transfected with Myc-Sox2 and the indicated COP1 truncates. The lysates were collected and subjected to immunoprecipitation with anti-Flag. The immunoprecipitates were then blotted. e Overview of the structure of Sox2 wild type and different VP mutants. Recombinant proteins (His-COP1, GST-Sox2, GST-Sox2-A1, GST-Sox2-A2, and GST-Sox2-AA) were expressed and purified. GST-Sox2 bound to glutathione-Sepharose 4B beads was incubated with His- COP1 for 24 h at 4 °C. Then the beads were washed and proteins were eluted, followed by western blotting. f HEK293T cells were transfected with indicated constructs. The lysates were collected and blotted with anti-Flag and anti-Myc antibody. The representative images are shown from three independent experiments. Unprocessed original scans of blots are shown in Supplementary Fig. 9
