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: Pathology
[{'content': 'The shape of RBC is biconcave due to? \nSelect and explain. \nA. Ankyrin, B. Spectrin, C. Band protein, D. Glycophorin-C', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Membrane proteins of RBC\n\nThere are following membrane proteins of RBC:\n\n(A) Integral proteins\n\nThese are embedded in membrane via hydrophobic interactions with lipids\nIntegral proteins are:\n\n(1) Band-3: It has two functions:\n\nAnionic transport: Exchange bicarbonate for chloride\nStructural: Linkage of the lipid bilayer to underlying membrane skeleton and important for prevention of surface loss.\n\n(2) Glycophorins: Imparts a negative charge to the cell, reducing interaction with endothelium and other cells.\n(3) Aquaporin 1: These selective pores for water transport allow RBC to remain in osmotic equilibrium with ECF.\nI) Peripheral membrane proteins\n\nThese are located on the cytoplasmic surface of the lipid bilayer and constitute membrane cytoskeleton.\nThese are anchored via integral proteins\nThese are responsible for elastibility and maintenance of RBC shape & stability. Important peripheral proteins are:\n\n\nSpectrin: It is the chief protein component and is responsible for the biconcave shape of RBC.\nActin: Spectrin tail is associated with actin filament.\nProtein 4.1: Stabilizes actin-spectrin interactions.\nAdducin: Stabilizes actin-spectrin interactions.\nAnkyrin: Interacts with band 3 and spectrin to achieve linkage between bilayer and skeleton. It is aug\xadmented by protein 4.2.', 'role': 'assistant'}]