BIOC 311 Lecture Notes - Lecture 19: Hmg-Coa Reductase, Farnesyl Pyrophosphate, Acetyl-Coa
12 Feb 2020
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From the data today, only 1/3 of your cholesterols comes from your diet, 2/3 come from the liver, there is some homeostatic balance. Remember: cholesterol starts with accoa and nadph. 2 accoa are converted to acetoacetyl-coa (we saw this in the ketose pathway) Combine with another acetyl coa 3-hydroxy-3-methylglutanyl-coa (hmg-coa) Hmg-coa + 2 nadph + 2h+ mevalonate + 2nadp+ + coa via hmg coa reductase: hmg-coa reductase is the key regulatory step. Use a lot of atp to make dimethylacyl pyrophosphate. Combine with isopentyl pyrophosphate to make farnesyl pyrophosphate: this is a molecule that can act as a lipid anchor. Total energy usage: 36 atp + 16 nadph per molecule: precious molecule to recycle rather than break down. Energy state: energy state of the cell, cholesterol concentration in cell, ampk (amp-dependent kinase) will convert hmg coa reductase to its inactive form. Amp: signal that the body is in a low energy state don"t use atp to make cholesterol!
