Cholesterol

Cholesterol

Lipid

Non polar

Precursor of

Bile acids

Hormines steroids

Vitamin D

Component

Membranes cells

Mammalian

Humans synthesize

1 g/day

Gets

Exogenous

Diet

Endogenous

Biosynthesis

Acetil- CoA

Mevalonic

Isopentenyl PP

Geranyl PP

Farnesyl PP

Squalene

2,3 -oxidosqualene

Lanosterol

Molecule amphiphilic

Enzymes involved in the pathway

Enzyme thiolase

HMG - CoA synthase

HMG - CoA reductase

acetyl-coenzyme A

acetyltransferases (ACAT)

acetyltransferases (ACAT)

acetoacetyl-CoA

42 kDa homodimeric protein

catalyzes the irreversible condensation of acetyl-CoA

3-hydroxy-3-methylglutaryl-CoA (HMG-CoA)

3-Hydroxy-3-methyl-glutaryl-CoA reductase

catalyzes the NADP-dependent

At the end of the process it produces

CoASH

Mevalonate

oxidized cofactor (NAD+ or NADP+)

the point of feedback control

mevalonate pathway

ATP-Dependent Enzymes

Cholesterol Pathway

Mevalonate Kinase MK

Phosphomevalonate Kinase

Farnesyl Diphosphate Synthase

Farnesyl Diphosphate Synthase

Squalene Synthase

Squalene Monooxygenase

Transport

Lipoproteins

Removes excess

Reverse cholesterol transport RCT

the intestine and liver

synthesize the protein Apo A-1

Gather cholesterol and phospholipids

HDL-c

catalyzed by the enzyme Lecithin-cholesterol acyltransferase

Liver

direct

Indirect

SR-B1

transfer of its cholesterol content

The resulting

transfer of its cholesterol content

Apo B-100

LDL

enzyme cholesteryl ester transfer protein (CETP)

By triacylglycerol molecules

Values

500 mg/dL

200 - 499 mg/dL

150- 199 mg/dL

150 mg/dL

Very high

High

Limit

Optimum