Which of the following drugs inhibit(s) ATP-ADP translocase?
Options:
(A) Oligomycin
(B) Atractyloside
(C) Amytal
(D) Bongkrekic acid
Official Answer Key:
B;D
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2026 Q.28)**
**1. Governing Concept**:
- **Topic**: Biochemistry & Mitochondrial Oxidative Phosphorylation Inhibitors
- The **Adenine Nucleotide Translocase (ANT / ATP-ADP translocase)** is an antiporter in the mitochondrial inner membrane that exchanges matrix ATP$^{4-}$ for cytosolic ADP$^{3-}$.
- Specific physiological and pharmacological inhibitors of ANT include:
1. **Atractyloside** and **Carboxyatractyloside**: Lock the translocase in the cytosol-facing ("c"-conformation).
2. **Bongkrekic acid**: Locks the translocase in the matrix-facing ("m"-conformation).
**2. Option Analysis**:
- **Option (A) [Oligomycin] is INCORRECT**: Oligomycin binds to and inhibits the $F_o$ proton channel of mitochondrial ATP synthase ($F_oF_1$-ATPase), not the translocase.
- **Option (B) [Atractyloside] is CORRECT**: Classic plant diterpene glycoside toxin that specifically blocks ANT on the intermembrane space side.
- **Option (C) [Valinomycin] is INCORRECT**: Valinomycin is a potassium-selective ionophore that uncouples the electrical gradient ($\Delta \Psi$) across membranes.
- **Option (D) [Bongkrekic acid] is CORRECT**: Respiratory toxin produced by *Burkholderia gladioli* pathovar *cocovenenans* that specifically binds and inhibits ANT from the matrix side.
**3. Final Answer**:
- **Correct Options**: **B, D**
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.