What typically happens to misfolded proteins during trafficking?

Misfolded proteins are typically tagged for degradation by the proteasome as a quality control mechanism within the cell. When proteins are synthesized, they must fold into specific three-dimensional shapes to function properly. If a protein fails to achieve its correct conformation, it can disrupt cellular processes and lead to the formation of aggregates that may be harmful to the cell. To prevent the accumulation of these potentially toxic misfolded proteins, cells utilize the ubiquitin-proteasome system.

In this process, misfolded proteins are tagged with ubiquitin molecules, which serve as a signal for the proteasome, a large proteolytic complex, to recognize and degrade the misfolded proteins into smaller peptides. This action not only helps maintain cellular health by removing defective proteins but also salvages amino acids for reuse in synthesizing new proteins. By effectively managing misfolded proteins in this way, cells ensure that only properly folded and functional proteins are allowed to proceed through the trafficking pathways toward their final destinations.