Understanding proteasome assembly and regulation: importance to cardiovascular medicine - PubMed (original) (raw)

Figure 2. The model of cardiac proteasomes

Cardiac proteasome complexes were purified from the murine heart by multidimensional chromatography and analyzed by mass spectrometry to yield a profile of components. The mammalian heart displays a heterogeneous mix of proteasomes, as all14 constitutive subunits (α1, α2, α3, α4, α5, α6, α7, β1, β2, β3, β4, β5, β6, β7) and all three of the inducible subunits (β1i, β2i, β5i) were found in the 20S proteasomes. Of the 19S proteasome complex, a total of 19 subunits have been identified. The six ATPase subunits include Rpt1, Rpt2, Rpt 3, Rpt4, Rpt5 and Rpt 6. The remaining 19S subunits are all non-ATPases and include Rpn1, Rpn2, Rpn3, Rpn4, Rpn5, Rpn6, Rpn7, Rpn8, Rpn9, Rpn10a and its isoform Rpn10b, Rpn11, Rpn12 and S5b. In addition to the 19S activator, the three subunits of the 11S activator (PA28α, PA28β, PA28γ), PI31 inhibitor and the PA200 regulatory complexes were also found associated with the purified proteasomes. These proteomic analyses of proteasome complexes helped us understand the mechanistic insights of this protein degradation machinery. Our investigations demonstrate that cardiac proteolytic function is regulated via at least three mechanisms, i.e., molecular organization, post-translational modification and the associating partners of the cardiac proteasomes (Gomes et al. 2006).