Question

Nerve cells require a source of free energy to transport vesicles containing neurotransmitters along the length of the axon, where mitochondria are scarce. Explain why it makes sense that glyceraldehyde3-phosphate dehydrogenase is located on the surface of some transport vesicles.

Short answer

The phosphorylation and the dephosphorylation reaction of glyceraldehyde-3-phosphate catalyzed glyceraldehyde3-phosphate dehydrogenase provide energy for axonal transport.

Step-by-step solution

Neurotransmitter

A neurotransmitter is an endogenous chemical transmitter that sends signals from one neuron to another target neuron across the chemical synapse.

Presence of glyceraldehyde-3-phosphate dehydrogenase on the surface of the neuron

The phosphorylation and dephosphorylation reactions are activated in cells that contain glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH catalyzes the phosphorylation process of glyceraldehyde-3-phosphate on the surface of neuron-transport vesicles. The phosphorylation step produces 1, 3-biphosphoglycerate, which phosphorylates ADP to produce ATP once more.

Hence, the phosphorylation process provides the energy for axonal transport, which produces ATP.