FIG. 5.

hHR23 inhibits degradation of ubiquitylated p53 and of ubiquitylated Hdm2. (A) Radiolabeled p53 was ubiquitylated by the E6/E6-AP complex. After 1 h, untreated RRL was added as a source of the 26S proteasome and degradation of ubiquitylated p53 studied in the absence (−) or in the presence (+) of the hHR23 forms indicated. (B) Radiolabeled Hdm2 was ubiquitylated in the presence of GST-Hdm2. Degradation of ubiquitylated Hdm2 was tested as described in panel A for p53. The running positions of the ubiquitylated forms of p53 and Hdm2 are indicated by a double asterisk.