The two primary pathways of protein degradation in cells are the ubiquitin-proteasome system and the autophagy-lysosome pathway.
1. Ubiquitin-Proteasome System (UPS): Proteins are tagged with ubiquitin molecules, marking them for degradation by the proteasome. This pathway is highly specific and tightly regulated.
2. Autophagy-Lysosome Pathway: This process involves the sequestration of proteins and organelles into autophagosomes, which then fuse with lysosomes where the contents are degraded. Autophagy can be a double-edged sword in cancer, acting as a tumor suppressor mechanism in some contexts while promoting survival in established tumors.
