Citrate-malate antiport carrier

The synthesis of fatty acids takes place in the cytosol but the precursor acetyl-CoA is produced in the M compartment. Acetyl-CoA cannot pass through the inner membrane of the mitochondrion but the acetyl group is transferred across the membrane as citrate by the citrate-malate antiport carrier (Figure 15.5). Acetyl-CoA, produced from this citrate in the cytosol by the action of ATP citrate... 

Transported as citrate via the citrate-malate antiport carrier... 

Fatty acids are generated cytoplasmically while acetyl-CoA is made in the mitochondrion by pyruvate dehydrogenase.This implies that a shuttle system must exist to get the acetyl-CoA or its equivalent out of the mitochondrion. The shuttle system operates in the following way Acetyl-CoA is first converted to citrate by citrate synthase in the TCA-cycle reaction. Then citrate is transferred out of the mitochondrion by either of two carriers, driven by the electroos-motic gradient either a citrate/phosphate antiport or a citrate/malate antiport as shown in Figure 2-2. 

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