obsolete mitochondrial respiratory chain complex I https://github.com/geneontology/go-ontology/issues/27253 true GO:0005748 cellular_component The reason for obsoletion is that this term unnecssarily specified a cellular compartment. GO:0005747 OBSOLETE. A protein complex located in the mitochondrial inner membrane that forms part of the mitochondrial respiratory chain. It contains about 25 different polypeptide subunits, including NADH dehydrogenase (ubiquinone), flavin mononucleotide and several different iron-sulfur clusters containing non-heme iron. The iron undergoes oxidation-reduction between Fe(II) and Fe(III), and catalyzes proton translocation linked to the oxidation of NADH by ubiquinone. respiratory chain complex I