Protein Function Regulation: Degradation Mechanisms

This lecture discusses the life cycle of proteins, focusing on their degradation mechanisms. It begins by explaining that proteins, like mRNA, have varying half-lives and can become damaged or misfolded over time. The instructor outlines two primary pathways for protein degradation: the proteasome and autophagy. The proteasome targets correctly folded proteins and small misfolded proteins, while larger aggregates are processed by autophagosomes. The lecture details the role of ubiquitin ligases, specifically E1, E2, and E3, in tagging proteins for degradation. The instructor emphasizes the regulatory mechanisms that control the activity of these ligases, including phosphorylation and ligand binding. Additionally, the lecture covers how the degradation signal on proteins can be activated or modified to facilitate recognition by ubiquitin ligases. The autophagosome's function is also explained, highlighting its role in enclosing materials for degradation by lysosomes. The lecture concludes with a summary of the protein life cycle, including translation, folding, maturation, localization, and regulation of activity and degradation.