Question

describe the non-lysosomal pathway of protein degradation in plant

Answer 1

The major pathway of selective protein degradation in eukaryotic cells uses ubiquitin as a marker that targets cytosolic and nuclear proteins for rapid proteolysis (Figure 7.39). Ubiquitin is a 76-amino-acid polypeptide that is highly conserved in all eukaryotes (yeasts, animals, and plants). Proteins are marked for degradation by the attachment of ubiquitin to the amino group of the side chain of a lysine residue. Additional ubiquitins are then added to form a multiubiquitin chain. Such polyubiquinated proteins are recognized and degraded by a large, multisubunit protease complex, called the proteasome. Ubiquitin is released in the process, so it can be reused in another cycle. It is noteworthy that both the attachment of ubiquitin and the degradation of marked proteins require energy in the form of ATP.