The “apyrase chase” reaction with CK1α, Nedd8–CRL4CRBN, UbcH5c, and Cdc34b. Priming reactions were carried out for indicated times followed by elongation with Cdc34 for 3 min at 37 °C. Reactions are carried out and analyzed as described for Figure 3C. CK1α, casein kinase 1α; CRBN, cereblon; CRL, Cullin–RING E3 Ub ligase; Nedd8, neural precursor cell expressed, developmentally downregulated 8.