Question

How many ATPs are synthesized for every cytoplasmic NADH that participates in the glycerophosphate shuttle in insect flight muscle?

Short answer

For every cytoplasmic NADH that participates in the glycerophosphate shuttle in insect flight muscle, 1.5 ATPs are synthesized.

Step-by-step solution

Concept of glycerophosphate shuttle

The glycerol-3-phosphate shuttle transports NADH produced in the cytosol by glycolysis to the mitochondria's oxidative phosphorylation pathway, which generates ATP.

Participates of in the glycerophosphate shuttle.

In this shuttle, a cytoplasmic glycerol--phosphate dehydrogenase 1 (Gpd or cGPDH) converts dihydroxyacetone phosphate (DHAP) to glycerol-3-phosphate (G- 3 P) by oxidizing one molecule of NADH (nicotinamide adenine dinucleotide hydride) to NAD +. A mitochondrial glycerol-3-phosphate dehydrogenase (Gpd or mGPDH) converts G-3-P back to DHAP by reducing one molecule of flavin adenine dinucleotide (FAD) to FADH₂. FADH₂ then enters mitochondrial respiration by converting ubiquinone (coenzyme Q) to ubiquinol (QH₂), which is ultimately converted to adenosine-triphosphate (ATP). Thus, 1.5 ATP are produced per NADH molecule.