Transport of Fatty Acids into Mitochondria Is Regulated

Transport of Fatty Acids into Mitochondria Is Regulated 

The level of fatty acids in the bloodstream is one factor that dictates how much fatty acid is delivered to a tissue. Further controls are necessary in the cell to regulate the utilization 

Fatty acids taken into cells are first activated in the cytosol by reaction with CoA and ATP to yield fatty acyl-CoA in a reaction catalyzed by acyl-CoA ligase  

The acyl-CoAs can penetrate the outer membrane of mitochondria through a pore but cannot be transported into mitochondria where /3 oxidation occurs. They must first be converted to their carnitine derivatives, which can be transported across the inner membrane of the mitochondria. 

Acyl-CoA is not transported across the inner membrane of the mitochondrion. Instead, the acyl-CoA reacts with carnitine to yield the acyl-carnitine derivative. This reaction is catalyzed by carnitine acyltransferase I, which is located on the outer mitochondrial membrane. The acyl-carnitine is transported across the inner membrane by a specific carrier protein. Once inside the matrix of the mitochondrion, the acyl-carnitine is converted back to its acyl-CoA 

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