Which of the following answers best describes the sequence of events carried out by enzymes E1, E2, and E3 in the ubiquitin-proteasome pathway?
A. E1 transfers ATP to target proteins, E2 processes target proteins, and E3 degrades proteins through ATP-dependent complexes.
B. E1 senses cellular stress and activates E2, which phosphorylates E3 to conjugate ubiquitin to proteins to target them for post-translational modifications like acetylation.
C. E1, E2, and E3 are all redundant in their activity within the protein destruction pathway; each covalently attach ubiquitin to target proteins to mark them for degradation by the proteasome.
D. E1 activates ubiquitin molecules, E2 carries activated ubiquitin molecules to E3, and E3 covalently attaches activated ubiquitin molecules to a protein to mark it for degradation by a protease complex.
E. E1 activates autophagosomes which fuse with proteins marked for degradation. E2 adds ubiquitin molecules to proteins within the autophagosome, and E3 activates acids to degrade the marked proteins.