Lipids occur in a number of forms (eg triglycerides, phospholipids, glycolipids, and cholesterol) and play vital roles in the cell. They contribute to energy storage, membrane structure and intracellular signalling.
Triacylglycerol is hydrolysed by hormone-sensitive lipase to release fatty acids and glycerol. Glycerol --> dihydroxyacetone phosphate --> glucose or pyruvate
Phospholipids are a major component of lipid membranes and surfactant. As well as serving a structural role, they are also involved in intracellular signalling.
Glycolipids are the sugar-containing lipids, such as gangliosides, which are components of lipid membranes.
Inherited defects in the sugar hydrolases and other enzymes involved in glycolipid turnover result in some of the lysosomal Storage Diseases, such as those of Gaucher, Niemann-Pick, Fabry, Tay-Sachs and metachromatic leukodystrophy. The clinical picture depends on the severity of the enzyme defect, and on the nature and location of the accumulated. lipid.
Cholesterol is a structural component of lipid membranes and the precursor for steroid hormone synthesis.
Familial hypercholesterolemia (FH)
Type IIa, Autosomal dominant
monogenic disorder; LDL receptor dysfunction
heterozygote prevalence is 1/500; homozygous FH is rare
raised cholesterol; Archilles tendon xanthomata and xanthelasma
Rx - Drugs
LDL-lowering apheresis (plasma exchange)