Figure 2.

Inhibition of CRL4^CRBN-dependent CK1α ubiquitination by compound KH-4-43. Lenalidomide is required for interactions between substrate receptor CRBN and neo-substrates that include CK1α (25, 26). The detailed procedure is described under “Experimental Procedure.” Low-intensity image of the substrate is also shown to better indicate substrate utilization. Species∗ most likely represents auto-phosphorylated form of CK1α (27). The substrate levels after reactions were quantified and shown. Note that similar inhibition of the CRL4^CRBN-dependent CK1α ubiquitination by KH-4-43 was observed in more than a dozen of independent experiments, including those shown in Figures 3C and 4, underscoring a highly reproducible effect.