This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'False statement about bilirubin is \nSelect and explain. \nA. Bilirubin circulating in plasma by covalently binding with albumin, B. Bilirubin is taken up across the sinusoidal (basolateral) membrane of hepatocytes by a carrier-mediated mechanism, C. Conjugated bilirubin in plasma undergoes stool elimination, D. Conjugated bilirubin is then directed primarily toward the canalicular (apical) membrane', 'role': 'user'}, {'content': "Answer: C \nExplanation: Bilirubin transpo: Bilirubin circulates in plasma noncovalently, bound to albumin. It is taken up across the sinusoidal membrane of hepatocytes by a carrier-mediated mechanism. Bilirubin uptake is mediated by a liver-specific sinusoidal organic anion transpo protein, (OATP1B1, SLC21A6) Then bilirubin is directed by cytosolic binding proteins (e.g., glutathione S-transferase B, fatty acid binding protein) to the ER. It is conjugated with uridine diphosphate (UDP)-glucuronic acid by the enzyme bilirubin UDP-glucuronyl transferase (B-UGT). Conjugated bilirubin is directed toward the canalicular membrane, and it is transpoed into the bile canaliculus by an adenosine triphosphate (ATP)-dependent pump. The responsible protein is multidrug resistance-associated protein-2 (MRP2, ABCC2) Small amounts of bilirubin glucuronides are secreted across the sinusoidal membrane MRP3 (ABCC3) Conjugated bilirubin in plasma undergoes renal elimination Ref: Sleisenger and Fordtran's, E-9, P-324", 'role': 'assistant'}]