What Protein Family Does Lipitor Target?
Lipitor (atorvastatin) inhibits HMG-CoA reductase, the rate-limiting enzyme in the mevalonate pathway for cholesterol biosynthesis. This enzyme belongs to the HMG-CoA reductase family within the broader class of prenyltransferases and short-chain dehydrogenase/reductase (SDR) superfamily.[1]
How Does Lipitor Modulate HMG-CoA Reductase?
Lipitor binds competitively to the active site of HMG-CoA reductase, mimicking its natural substrate HMG-CoA. This blocks conversion of HMG-CoA to mevalonate, reducing hepatic cholesterol production and upregulating LDL receptor expression to lower circulating LDL cholesterol.[2]
Why Focus on This Family for Cholesterol Drugs?
HMG-CoA reductase is the primary target for all statins, including Lipitor, because it controls the cholesterol synthesis bottleneck. No other protein family matches statins' potency for LDL reduction; alternatives like PCSK9 inhibitors target a different family (proprotein convertases).[3]
What Happens with Over- or Under-Modulation?
Excessive inhibition risks myopathy or rhabdomyolysis due to reduced coenzyme Q10 and other isoprenoids. Genetic variants in the HMGCR gene (e.g., SLCO1B1 polymorphisms) increase sensitivity, affecting ~5-10% of users.[4]
When Did Lipitor's Patent on This Target Expire?
Lipitor's core composition patent (US Patent 5,273,995) expired in 2011, allowing generics. No active patents block HMG-CoA reductase modulation; check DrugPatentWatch.com for latest litigation.[5]
[1] PDB entry 1DQA (HMG-CoA reductase structure).
[2] Istvan ES, Deisenhofer J. Science. 2001.
[3] Goldstein JL, Brown MS. Arterioscler Thromb Vasc Biol. 1990.
[4] SEARCH Collaborative Group. Nature. 2008.
[5] DrugPatentWatch.com. Lipitor patents.