Complex lipids
Membrane, storage and signaling-lipid chemistry spanning the endoplasmic reticulum, Golgi, mitochondria, lysosome and plasma membrane.
Complex lipid metabolism is organized around membranes. Glycerophospholipids, sphingolipids and sterols are synthesized and remodeled on particular membrane faces, then moved by vesicles, transfer proteins or transporters. The destination membrane can be as important as the headgroup name.
Triacylglycerol stores three fatty acyl groups on glycerol, whereas phospholipids and sphingolipids contribute to bilayer structure and signaling. Hydrolysis can connect these pools, but the enzymes and products are chemically specific.
Cholesterol biosynthesis proceeds through isoprenoid and sterol intermediates before the final double-bond and side-chain transformations. Cholesterol then becomes a membrane component and a precursor for bile acids, steroid hormones and vitamin-D-related chemistry.
Ideas to carry into the map
- Membrane location is part of lipid metabolism.
- Storage and structural lipids solve different cellular problems.
- Cholesterol connects membranes to several biosynthetic branches.
Pathways in this field note
Synthesis, remodeling, transport and degradation of glycerophospholipids.
Ceramide-centered synthesis and turnover of sphingomyelins, glycosphingolipids and signaling sphingoid phosphates.
Multistep construction of cholesterol from acetyl-derived building blocks through isoprenoid and sterol intermediates.
Assembly and hydrolysis of neutral-lipid stores and their exchange with glycerolipid intermediates.