Ubiquitination of Damaged Proteins

The video explains the ubiquitination process, where damaged proteins are tagged with ubiquitin for degradation. It details the roles of E1, E2, and E3 enzymes in transferring ubiquitin to lysine residues on proteins, forming an amide bond. The process requires ATP to facilitate energy transitions. Polyubiquitination signals the cell to degrade the protein using a proteasome, recycling amino acids for new protein synthesis.

What is the primary function of ubiquitination in cells?

• To increase protein stability

• To enhance protein synthesis

• To signal the degradation of damaged proteins

• To facilitate protein folding

Which enzyme is responsible for attaching ubiquitin to the damaged protein?

• Proteasome

• E3

• E2

• E1

What is the role of E1 in the ubiquitination process?

• It activates ubiquitin by attaching an adenosine monophosphate

• It degrades the ubiquitinated protein

• It transports ubiquitin to the proteasome

• It directly attaches ubiquitin to the damaged protein

Why is ATP necessary in the ubiquitination process?

• To degrade the ubiquitinated protein

• To provide energy for the formation of a thioester bond

• To stabilize the ubiquitin molecule

• To directly attach ubiquitin to lysine residues

What is polyubiquitination?

• The attachment of multiple ubiquitin molecules to a protein

• The degradation of ubiquitin molecules

• The attachment of a single ubiquitin molecule to a protein

• The removal of ubiquitin from a protein

What is the role of the proteasome in the cell?

• To synthesize new proteins

• To transport proteins across the cell membrane

• To attach ubiquitin to proteins

• To degrade polyubiquitinated proteins

What happens to the amino acids after a protein is degraded by the proteasome?

• They are used to produce energy

• They are stored in the cell

• They are excreted from the cell

• They are recycled to build new proteins