Acc

Definition

ACC, or Acetyl-CoA Carboxylase, is an enzyme that plays a crucial role in fatty acid synthesis by converting acetyl-CoA into malonyl-CoA, a key building block in the formation of fatty acids. This process is essential because it not only initiates fatty acid synthesis but also regulates energy metabolism and lipid homeostasis in cells. ACC is activated by citrate and inhibited by long-chain fatty acyl-CoAs, making it an important regulatory point for lipid metabolism.

5 Must Know Facts For Your Next Test

1. ACC is a biotin-dependent enzyme, meaning it requires biotin as a cofactor for its carboxylation activity.
2. The regulation of ACC is critical for maintaining energy balance; when energy levels are high, ACC promotes the storage of fats.
3. ACC exists in two isoforms, ACC1 and ACC2, with different tissue distributions and roles in metabolism.
4. Inhibition of ACC has been studied as a potential therapeutic strategy for obesity and metabolic disorders due to its central role in fat synthesis.
5. ACC activity can be affected by hormonal signals; for instance, insulin stimulates its activity while glucagon has the opposite effect.

Review Questions

• How does ACC influence the regulation of fatty acid metabolism?
  • ACC influences fatty acid metabolism by converting acetyl-CoA to malonyl-CoA, which is critical for initiating fatty acid synthesis. When energy levels are high, citrate activates ACC, promoting fat storage and synthesis. Conversely, long-chain fatty acyl-CoAs inhibit ACC, preventing excess fat accumulation when energy stores are sufficient. This regulation helps maintain lipid homeostasis within the body.
• Discuss the significance of ACC's dual regulation by citrate and long-chain fatty acyl-CoAs.
  • ACC's dual regulation is significant because it allows the enzyme to respond dynamically to the cell's energy status. Citrate serves as a signal of high energy availability, promoting the conversion of excess acetyl-CoA into malonyl-CoA for fatty acid synthesis. In contrast, long-chain fatty acyl-CoAs act as feedback inhibitors when fat stores are adequate, preventing unnecessary lipid accumulation. This regulatory mechanism ensures that fatty acid synthesis aligns with metabolic needs.
• Evaluate the potential impact of targeting ACC in therapeutic strategies for metabolic diseases.
  • Targeting ACC presents a promising therapeutic strategy for managing metabolic diseases such as obesity and type 2 diabetes. By inhibiting ACC, researchers aim to reduce fatty acid synthesis and promote the use of existing fat stores for energy, potentially leading to weight loss and improved insulin sensitivity. However, careful consideration is needed to balance this approach since inhibiting ACC could also disrupt normal lipid homeostasis and lead to adverse effects on overall metabolism. The complexities of ACC's regulatory mechanisms must be thoroughly understood before implementing such treatments.

Related terms

Fatty Acid Synthase: A multi-enzyme complex that catalyzes the synthesis of fatty acids from acetyl-CoA and malonyl-CoA, producing long-chain fatty acids.

Malonyl-CoA: The product of ACC activity, malonyl-CoA is a key intermediate in fatty acid biosynthesis and serves as a substrate for fatty acid synthase.

Citrate: A metabolite that acts as an allosteric activator of ACC, promoting fatty acid synthesis when energy levels are sufficient.