Proteasome activity is regulated at multiple levels, including the expression of proteasome subunits, post-translational modifications, and the presence of regulatory proteins. For example, phosphorylation and ubiquitination of proteasome subunits can modulate their activity. Additionally, proteins such as PA28 and PA200 can bind to the proteasome and alter its substrate specificity and catalytic activity. This regulation ensures that proteasome activity is finely tuned to meet the cellular needs.
