What is the primary role of ubiquitin in protein metabolism?

A To synthesize new proteins
B To degrade damaged or misfolded proteins ✓
C To transport proteins across cell membranes
D To store proteins in the cell

Explanation

Ubiquitin plays a crucial role in marking damaged or misfolded proteins for degradation by the proteasome, helping to maintain protein homeostasis in the cell.

Source

Alberts et al., Molecular Biology of the Cell
Protein Metabolism Biochemistry Protein Degradation Medium MEDICAL Confidence: high