Knowra Lipid raft Lipid raft A dynamic, nanoscale membrane region enriched in cholesterol, sphingolipids, and selected proteins. Its composition can organize signaling and trafficking, though its size and stability depend on experimental conditions.
Lipid bilayer : A membrane structure made of two lipid layers, with water-attracting heads facing outward and water-repelling tails inward. Rafts are proposed domains within this broader membrane structure.
G protein-coupled receptor : A cell-surface receptor that activates intracellular signaling by coupling to heterotrimeric G proteins. Some receptors and signaling partners partition into raft-like regions, affecting their local interactions.
Kai Simons : A German cell biologist known for work on membrane organization, epithelial polarity, and lipid rafts. Simons helped develop the raft hypothesis and connect it to membrane trafficking.
Fluid mosaic model : A model describing membranes as fluid lipid bilayers containing laterally mobile proteins. Raft models add persistent compositional organization to the fluid-membrane picture.
Cholesterol : A sterol that modulates membrane order and permeability and serves as a precursor to steroid hormones. Its interactions with saturated lipids help shape raft-like membrane organization.
T cell receptor : A receptor complex on T lymphocytes that recognizes antigen fragments presented by major histocompatibility proteins. Raft-associated reorganization has been studied during T-cell receptor signaling.
Detergent-resistant membrane : A membrane fraction that remains insoluble under particular detergent-extraction conditions. Early raft research often used these fractions as biochemical evidence for ordered membrane domains.
Membrane phase separation : The segregation of membrane components into coexisting regions with different physical properties or compositions. Phase separation can create ordered domains, but does not establish that cellular rafts are stable phases.
Sphingolipid : A class of membrane lipids built around a sphingoid backbone, including sphingomyelin and glycosphingolipids. Many raft-enriched lipids have long, saturated chains that interact favorably with cholesterol.
Caveola : A small, flask-shaped plasma-membrane invagination enriched in cholesterol and caveolin proteins. Caveolae are distinct structures often discussed alongside, but not equated with, lipid rafts.
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