Protein Metabolism | Ubiquitination of Proteins & the 26S Proteasome

The video tutorial explains the process of ubiquitination and the ubiquitin ligase system, detailing how proteins are marked for degradation. It covers the role of the proteasome in breaking down proteins and recycling amino acids, emphasizing the importance of this process in cellular function.

What is the primary function of ubiquitination in the cell?

• To modify protein structure

• To transport proteins across membranes

• To signal the destruction of proteins

• To synthesize new proteins

Which enzyme in the ubiquitin ligase system is responsible for attaching ubiquitin to the substrate protein?

• E1

• E2

• E3

• E4

What is the role of E2 in the ubiquitin ligase system?

• To bind the substrate protein

• To synthesize ubiquitin

• To transfer ubiquitin from E1 to E3

• To degrade the protein

How many times is a protein typically ubiquitinated before it is targeted for degradation?

• Multiple times

• Once

• Four times

• Twice

What is the primary function of the proteasome in the cell?

• To transport proteins

• To synthesize proteins

• To recycle amino acids

• To degrade ubiquitin-tagged proteins

What type of activity does the proteasome exhibit to degrade proteins?

• Lysosomal activity

• Trypsin-like activity

• Phosphatase activity

• Kinase activity

What determines the efficiency of protein degradation by the proteasome?

• The size of the protein

• The presence of ATP

• The number of ubiquitin molecules attached

• The sequence match with the proteasome