alpha keto glutarate
alpha keto glutaric acid

This substance in the citric acid cycle gets the most versatile action. It can cycle within the citrate cycle, as shown, or shunt off by becoming glutamine.

HC-CO OH
   |
HCH
   |
HC-NH₂
   |
  CO OH         Glutamine

Glutamine is a neurotransmitter. It is a precursor of Creatine Phosphate, a key energy shuttle in skeletal muscle. It is a precursor of Ornithine an important urea cycle component also leading to arginine and proline (important amino acids) and the polyamines. It is a precursor  of  the neurotransmitter gama-amino-butyric acid an important chemical in spasticity. It is a precursor of glutathione and folate polyglutamates. Glutamine is used as a direct neurotransmitter in the brain. In short, this is a very important link in the citric acid cycle.

To the degree that each substance is tied to glutaric acid is the degree to which mitochondria are important in that segment of metabolism.