FIGURE 8.

TRIM32 assembles polyubiquitin chains on Ubc5A. Autoradiogram of 80 nm purified Ubc5AC85S-¹²⁵I-ubiquitin oxyester (lanes 1–7) incubated with 80 nm Uba1 (lanes 2–7) and, where indicated, 100 nm wild type Ubc5A, and 5 μm unlabeled ubiquitin for 15 min at 37 °C before quenching with SDS sample buffer and SDS-PAGE resolution as described under “Materials and Methods.” Migration positions for relative molecular weight standards are shown to the left. The position of the 5% stacking gel, Ubc5AC85S-¹²⁵I-ubiquitin oxyester, and free ¹²⁵I-ubiquitin are shown to the right.