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isocitrate dehydrogenase, NADP-dependent, eukaryotic type This model describes a eukaryotic, NADP-dependent form of isocitrate dehydrogenase. These eukaryotic enzymes differ considerably from a fairly tight cluster that includes all other related isocitrate dehydrogenases, 3-isopropylmalate dehydrogenases, and tartrate dehydrogenases. Several NAD- or NADP-dependent dehydrogenases, including 3-isopropylmalate dehydrogenase, tartrate dehydrogenase, and the multimeric forms of isocitrate dehydrogenase, share a nucleotide binding domain unrelated to that of lactate dehydrogenase and its homologs. These enzymes dehydrogenate their substates at a H-C-OH site adjacent to a H-C-COOH site; the latter carbon, now adjacent to a carbonyl group, readily decarboxylates. This model does not discriminate cytosolic, mitochondrial, and chloroplast proteins. However, the model starts very near the amino end of the cytosolic form; the finding of additional amino-terminal sequence may indicate a transit peptide. [Energy metabolism, TCA cycle]
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