This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Biochemistry
[{'content': 'Ubiquitin role in: \nSelect and explain. \nA. Protein degradation, B. Protein synthesis, C. Protein folding, D. Protein transpoation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Proteins that are misfolded or destined for degradation are marked for destruction by , highly conserved protein called ubiquitin. Ubiquitinated proteins are rapidly degraded by a cytosolic complex known as the proteasome.', 'role': 'assistant'}]