Fatty acid synthesis is a process that creates fatty acids in the cytoplasm, primarily within the liver and fat cells. It involves a series of three main steps.
The Three Main Steps of Fatty Acid Synthesis
Here are the steps of fatty acid synthesis:
- The Citrate Shuttle: This is the initial step, which transports acetyl-CoA from the mitochondria to the cytoplasm. Acetyl-CoA, a key building block for fatty acids, is produced in the mitochondria. However, fatty acid synthesis occurs in the cytoplasm. Thus, the citrate shuttle is required to move acetyl-CoA to the correct location.
- Acetyl-CoA Carboxylase (Rate-Limiting Step): Once in the cytoplasm, acetyl-CoA is converted into malonyl-CoA by the enzyme acetyl-CoA carboxylase. This is a crucial regulatory step, often referred to as the rate-limiting step because it determines the overall speed of fatty acid synthesis.
- Fatty Acid Synthase Complex: Finally, the fatty acid synthase complex takes the malonyl-CoA molecules and uses them to build the fatty acid chain. This complex is responsible for the repetitive series of reactions that extend the fatty acid chain by two carbon atoms at a time using malonyl-CoA molecules.
| Step | Description |
|---|---|
| Citrate Shuttle | Transports acetyl-CoA from the mitochondria to the cytoplasm. |
| Acetyl-CoA Carboxylase | Catalyzes the rate-limiting conversion of acetyl-CoA to malonyl-CoA. |
| Fatty Acid Synthase Complex | Extends the fatty acid chain using malonyl-CoA, creating the final fatty acid product. |
In summary, fatty acid synthesis is a sequential process that requires the transfer of acetyl-CoA to the cytoplasm, its conversion to malonyl-CoA, and finally, the elongation of fatty acid chain by fatty acid synthase.
