GATE 2026 BT Q.28: solution and answer

Official answer: B, DSource: Official answer key, GATE 2026 BT (IIT Guwahati)

1. The ATP-ADP translocase (adenine nucleotide translocase, ANT) sits in the inner mitochondrial membrane. It exports ${\text{ATP}}^{4-}$ from the matrix and imports ${\text{ADP}}^{3-}$ in a 1:1 antiport.

2. (A) Oligomycin binds the $F_0$ proton channel of ATP synthase and blocks proton flow through it. It does not act on the translocase, so A is wrong.

3. (B) Atractyloside (and its relative carboxyatractyloside) binds ANT from the cytosolic side and locks it in the cytosol-facing conformation. This stops the exchange, so B is correct.

4. (C) Amytal (amobarbital) is a barbiturate that inhibits Complex I (NADH dehydrogenase) and so blocks electron transfer. It does not act on the translocase, so C is wrong.

5. (D) Bongkrekic acid binds ANT from the matrix side and locks it in the matrix-facing conformation. This also stops the exchange, so D is correct.

6. The two ANT inhibitors are therefore atractyloside and bongkrekic acid, which is options B and D.