Outer mitochondrial membrane

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The outer mitochondrial membrane, which encloses the entire organelle, has a protein-to-phospholipid ratio similar to the eukaryotic plasma membrane (about 1:1 by weight). It contains numerous integral proteins called porins, which contain a relatively large internal channel (about 2-3 nm) that is permeable to all molecules of 5000 daltons or less. Larger molecules can only traverse the outer membrane by active transport through mitochondrial membrane transport proteins. The outer membrane also contains enzymes involved in such diverse activities as the elongation of fatty acids, oxidation of epinephrine (adrenaline), and the degradation of tryptophan.

v • d • e Mitochondrial enzymes and transporters Outer membrane fatty acid degradation (Carnitine palmitoyltransferase I, Long fatty acyl CoA synthetase) tryptophan metabolism (Kynureninase) monoamine neurotransmitter metabolism (Monoamine oxidase) Intermembrane space Adenylate kinase - Creatine kinase Inner membrane oxidative phosphorylation (Coenzyme Q - cytochrome c reductase, Cytochrome c, NADH dehydrogenase, Succinate dehydrogenase) pyrimidine metabolism (Dihydroorotate dehydrogenase) mitochondrial shuttle (Malate-aspartate shuttle, Glycerol phosphate shuttle) other (Glutamate aspartate transporter, Glycerol-3-phosphate dehydrogenase, ATP synthase, Carnitine palmitoyltransferase II) Matrix citric acid cycle (Citrate synthase, Aconitase, Isocitrate dehydrogenase, Oxoglutarate dehydrogenase, Succinyl coenzyme A synthetase, Fumarase, Malate dehydrogenase) anaplerotic reactions (Aspartate transaminase, Glutamate dehydrogenase, Pyruvate dehydrogenase complex) urea cycle (Carbamoyl phosphate synthetase I, Ornithine transcarbamylase, N-Acetylglutamate synthase) alcohol metabolism (ALDH2) Mitochondrial DNA Complex I (7 units) - Complex III (1 unit) - Complex IV (3 units) - ATP synthase (2 units)