Q.12 Which one of the following is an ABC transporter?
(A)multidrug resistance protein (B) acetylcholine receptor
(C)bacteriorhodopsin (D) ATP synthase
The correct answer to the multiple-choice question is (A) multidrug resistance protein, as it belongs to the ATP-binding cassette (ABC) transporter family responsible for active transport across membranes.
Correct Answer
Multidrug resistance protein (MRP), such as MRP1 (ABCC1), functions as an ABC transporter by using ATP hydrolysis to efflux drugs and toxins from cells, contributing to multidrug resistance in cancer therapy. This primary active transport mechanism involves nucleotide-binding domains (NBDs) and membrane-spanning domains (MSDs) typical of ABC proteins.
Option Explanations
ABC transporters are a superfamily of membrane proteins that couple ATP binding and hydrolysis to move diverse substrates across lipid bilayers.
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(A) Multidrug resistance protein: This is an ABC transporter (e.g., ABCC1/MRP1, ABCB1/MDR1/P-glycoprotein), overexpressed in cancer cells to pump out chemotherapeutic agents, leading to drug resistance.
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(B) Acetylcholine receptor: This is a ligand-gated ion channel (nicotinic type) in the Cys-loop receptor family, mediating rapid synaptic transmission by allowing ion flow upon acetylcholine binding, not ATP-driven transport.
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(C) Bacteriorhodopsin: A light-driven proton pump in archaeal membranes, functioning as a retinal-based ion transporter via photoisomerization, unrelated to ABC mechanisms.
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(D) ATP synthase: An ATP-producing enzyme (F-type ATPase) that generates ATP via proton motive force during oxidative phosphorylation, not an ABC transporter despite ATP involvement.
This MCQ tests knowledge of membrane protein classification in biochemistry and microbiology, key for biotechnology students studying drug resistance and transport kinetics.
