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
Ubiquitin role in: 
Select and explain. 
A. Protein degradation, B. Protein synthesis, C. Protein folding, D. Protein transpoation
A: Protein degradation
Answer: A: Protein degradation 
Explanation: 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.