Fig. 4. Importance of Hsc70 and Hsp40 for CHIP-dependent ubiquitylation of heat-denatured luciferase. Luciferase was heated at 43°C for 10 min with Hsc70 and/or Hsp40 in the presence or absence of ATP, as described in Methods. The routine ubiquitylation assay by CHIP was carried out with UbcH5c and Ub (A) or GST–Ub (B), as described in Figure 1A.