Figure EV5. CSN catalysis on UNG2‐ and MERLIN‐bound N8‐CRL4^DCAF1 .

• A–C
  SEC‐MALS analysis including the peaks eluting near the SEC column void volume of (A) CRL4^DCAF1‐VPR, (B) CRL4^DCAF1‐VPR‐UNG2, and (C) CRL4^DCAF1‐MERLIN. The chromatogram shows the Rayleigh ratio curves together with the molar mass (MDa) determined by MALS.
• D
  A close‐up view of The CRL4^DCAF1‐CSN cryo‐EM map with fitted crystal structures of CUL4A (gray), RBX1 (red) (PDB 2HYE), DDB1 (blue)‐DCAF1 (WD40) (yellow), VPR (dark gray), and UNG2 (green) (PDB 5JK7).
• E, F
  Fluorescence polarization assay investigating the catalytic activity of CSN on N8‐CRL4^DCAF1(FL) when bound to (E) VPR‐UNG2 or (F) MERLIN. Initial rates (M/s) are plotted versus concentrations (M) of N8‐CRL4^DCAF1(FL)‐VPR‐UNG2 (magenta), N8‐CRL4^DCAF1(FL) (blue), and N8‐CRL4^DCAF1(FL)‐MERLIN (red). Column representation of K_cat values, and table summarizes K_M, K_cat, and V_max values calculated from the curves (biological replicates, n = 3, mean ± SD).