Carnitine-acylcarnitine translocase

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Carnitine-acylcarnitine translocases are responsible for transporting both carnitine and carnitine-fatty acid complexes into and out of the mitochondria, across the inner mitochondrial membrane.

[edit] Function

This enzyme is required as fatty acids cannot cross the mitchondrial membranes without assistance. The fatty acid is firstly bound to CoA to cross the external mitochondrial membrane. It then switches the CoA for carnitine by the use of the enzyme carnitine palmitoyl transferase I. The complex then uses facilitated diffusion by Carnitine-acylcarnitine translocase to enter the mitochondrial matrix. Here, the acylcartinine complex is disrupted by cartinine palmitoyl transferase II and the fatty acid rebinds to CoA. Cartinine then diffuses back across the membrane by a second carnitine-acylcarnitine translocase into the inter-mitochondiral membrane space. This is the cartinine shuttle system.

[edit] Clinical significance

A disorder is associated with carnitine-acylcarnitine translocase deficiency. This disorder prevents the shuttle-like action of cartinine from assisting fatty acids across the mitochondiral membrane and therefore there is decreased fatty acid metabolism. The result of this is an increased number of fat droplets within muscles and liver, decreased tolerance to long term excerise, inability to fast for more than a few hours, muscle weakness and wasting, strong acidic smell on breath (due to protein breakdown)

Acyl-CoA from cytosol to the mitochondrial matrix.gif

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