Outer mitochondrial membrane

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Cell biology
The mitochondrion
Mitochondrion mini.svg
Components of a typical mitochondrion

1 Outer membrane   ◄ You are here

1.1 Porin

2 Intermembrane space

2.1 Intracristal space
2.2 Peripheral space

3 Lamella

3.1 Inner membrane
3.11 Inner boundary membrane
3.12 Cristal membrane
3.2 Matrix
3.3 Cristæ

4 Mitochondrial DNA
5 Matrix granule
6 Ribosome
7 ATP synthase


The outer mitochondrial membrane, which encloses the entire organelle,60 to 75 Å thick. It 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, and mitochondrial preproteins are imported through specialised translocase complexes. 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. Outside the outer membrane there are small (Diameter:60Å) particles named sub-unit of Parson.

Enzymes in outer membrane[edit]

Some of the enzymes present in the outer membrane of mitochondria are, monoamine oxidase, rotenone-insensitive NADH-cytochrome c-reductase, kynurenine hydroxylase and fatty acid Co-A ligase etc.

See also[edit]

MITOL(mitochondrial ubiqutin ligase)is localized in the mitochondrial outer membrane.