<Li> PDK phosphorylates three specific serine residues on E1 with different affinities . Phosphorylation of any one of them renders E1 (and in consequence the entire complex) inactive . </Li> <Li> Dephosphorylation of E1 by PDP reinstates complex activity . </Li> <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>

Is a substrate in the reoxidation reaction of e3