Defective proteins are degraded after attaching covalently to-

The Ubiquitin-Proteasome Pathway (UPP) is the main & highly regulated mechanism for protein degradation. UBIQUITIN It is present in the cytoplasm and nucleus. Ubiquitin protein is highly conserved, small, globular, non-enzymic protein and is recycled which is used to degrade damaged or sho-lived or misfolded proteins. Uses ATP e - amino of Lysine in protein is attached with a covalent bond to C-terminal Glycine of ubiquitin. This bond is an isopeptide bond. Fig: The Ubiquitin-Proteasome pathway Regarding other Options: Pepsin is an endopeptidase and is one of the main digestive enzymes in the digestive systems of humans. Laminins critically contribute to cell attachment and differentiation, cell shape and movement, etc. Clathrin is a protein that plays a major role in the formation of coated vesicles.