<P> Products of the reaction act as allosteric inhibitors of the PDC, because they activate PDK . Substrates in turn inhibit PDK, and thus, reactivating PDC . </P> <P> During starvation, PDK increases in amount in most tissues, including skeletal muscle, via increased gene transcription . Under the same conditions, the amount of PDP decreases . The resulting inhibition of PDC prevents muscle and other tissues from catabolizing glucose and gluconeogenesis precursors . Metabolism shifts toward fat utilization, while muscle protein breakdown to supply gluconeogenesis precursors is minimized, and available glucose is spared for use by the brain . </P> <P> Calcium ion has a role in regulation of PDC in muscle tissue, because it activates PDP, stimulating glycolysis on its release into the cytosol - during muscle contraction . Some products of these transcriptions release H2 into the muscles . This can cause calcium ions to decay over time . </P> <P> In eukaryotic cells the pyruvate decarboxylation occurs inside the mitochondrial matrix, after transport of the substrate, pyruvate, from the cytosol . The transport of pyruvate into the mitochondria is via the transport protein pyruvate translocase . Pyruvate translocase transports pyruvate in a symport fashion with a proton, and hence is active, consuming energy . </P>

Which of the following compounds inhibits the pyruvate dehydrogenase complex