Question

list three major protein degradtion mechanism present in eukaryotic cell identify the difference between them &their difference in kind of protein substrete to be degrade

Answer 1

With the help of several methods proteins are degraded in eukaryotic cells. Some of the methods are listed below;

• Protein degradation by Lysosomal proteolysis: Lysosomes contains degrading enzymes, including several proteases. Most of the extracellular proteins are degraded after taken up by endocytosis.
• Membrane Proteins are degeraded by retrotranslocation: The proteins to be degraded are directed back into the cytoplasm from endoplasmic reticulum. Proteins are modified by polyubiquitin before degradation. Later proteins are degraded by proteosomes.
• Ubiquitin-Proteosome pathway: In this, proteins to be degraded are marked with ubiquitin. These marked polyubiquitin proteins are degraded by large protease complex such as proteosome. Attached ubiquitin is then released for further use. Nuclear proteins and cytosolic proteins are degraded by this method.