Figure 1.

Proteasome chymotrypsin-like activity is increased in the amygdala after fear conditioning. Rats were trained to auditory fear conditioning (n = 10–11 per group) and amygdala tissue collected 0.5, 1, 4, or 6 h later for in vitro proteasome activity assay and Western blotting. (A) Amygdala lysates collected 4 h after fear conditioning showed enhanced degradation of the fluorogenic substrate LLVY-AMC relative to homecage (HC) controls. (B) There were transient increases in proteasome subunit Rpt6 that returned to baseline levels by 4 h. (C) Lysine-48 linked polyubiquitination was increased from 1–4 h after fear conditioning. Lower right panel shows representative K48 polyubiquitin blots for each group from the same gel. ^*p < 0.05 from HC controls.