This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
How do proteins enter peroxisomes? 
Select and explain. 
A. Folded, using a C-terminal or internal signal sequence, B. Folded, using an N-terminal or internal signal sequence, C. Unfolded, using a C-terminal or internal signal sequence, D. Unfolded, using an N-terminal or internal signal sequence
A: Folded, using a C-terminal or internal signal sequence
Answer: A: Folded, using a C-terminal or internal signal sequence 
Explanation: Peroxisomal proteins are fully folded in the cytoplasm and enter the organelle in folded form. The most common signal sequence which directs proteins to peroxisomes is a C-terminal Ser-Lys-Leu tripeptide. Reference: Harper; 30th edition