Final answer:
The citric acid cycle proteins are located in the mitochondrial matrix, a compartment within the mitochondrion, where they play a key role in cellular energy production.
Step-by-step explanation:
The proteins involved in the citric acid cycle are located in the mitochondrial matrix. The mitochondrion is comprised of several compartments, but the citric acid cycle specifically occurs within the matrix. This compartment contains enzymes that facilitate the conversion of the six-carbon citrate molecule into a four-carbon molecule, oxaloacetate, which is at the start of the cycle. During these conversions, each citrate molecule produces high-energy molecules: one ATP, one FADH2, and three NADH, which are important for cellular energy production.