| 20S proteasome, essential component of protein degradation mechanism, is important to maintain homeostasis. Its malfunctions have been associated with several pathological conditions. This study presents an extensive study of murine cardiac 20S proteasome. Using biochemical methods, 20S proteasome have been purified to 95%. Proteomic study identified all 20S proteasome subunits. Endogenous phosphorylation was also documented. Furthermore, several associating kinases and phosphatase were identified. They regulated its activities. In PKCepsilon over-expression mice, 20S proteasome expression level was up-regulated, but its peptidase activities did not increase. alphaB crystallin were recruited to PKCepsilon subproteome in the transgenic mice, which also associated with 20S proteasome. This association was enhanced in the transgenic mice and has been reported to inhibit 20S proteasome activities. It suggested alphaB crystallin play a role in cardiac 20S proteasome regulation. |
