The γ‐aminobutyric acid receptor B, but not the metabotropic glutamate receptor type‐1, associates with lipid rafts in the rat cerebellum

• Published in: Journal of neurochemistry Vol. 79; no. 4; pp. 787 - 795
• Main Authors: Becher, Anja, White, Julia H., McIlhinney, R. A. Jeffrey
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-11-2001; Blackwell
• Subjects: Animals; beta-Cyclodextrins; Biological and medical sciences; brain; Cell Membrane - chemistry; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Centrifugation, Density Gradient; Cerebellum - chemistry; Cerebellum - metabolism; Cholesterol - chemistry; Cyclodextrins - chemistry; Cyclodextrins - pharmacology; detergent‐insoluble; Fundamental and applied biological sciences. Psychology; Glycolipids - chemistry; GTP-Binding Proteins - chemistry; lipid rafts; Membrane Microdomains - chemistry; Membrane Microdomains - metabolism; metabotropic GABA receptors; metabotropic glutamate receptors; microdomains; Octoxynol - chemistry; Octoxynol - pharmacology; Protein Binding - drug effects; Protein Binding - physiology; Protein Structure, Tertiary - drug effects; Protein Subunits; Rats; Rats, Wistar; Receptors, GABA-B - chemistry; Receptors, GABA-B - metabolism; Receptors, Metabotropic Glutamate - chemistry; Saponins - chemistry; Saponins - pharmacology; Solubility - drug effects; Vertebrates: nervous system and sense organs; Cerebellum; Vertebrata; Mammalia; Rat; Metabotropic receptor; Rodentia; Central nervous system; Glutamate receptor; Gabaergic receptor A; Brain (vertebrata)
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.2001.00614.x

Recent evidence suggests that specialized microdomains, called lipid rafts, exist within plasma membranes. These domains are enriched in cholesterol and sphingolipids and are resistant to non‐ionic detergent‐extraction at 4°C. They contain specific populations of membrane proteins, and can change their size and composition in response to cellular signals, resulting in activation of signalling cascades. Here, we demonstrate that both the metabotropic γ‐aminobutyric acid receptor B (GABAB receptor) and the metabotropic glutamate receptor‐1 from rat cerebellum are insoluble in the non‐ionic detergent Triton X‐100. However, only the GABAB receptor associates with raft fractions isolated from rat brain by sucrose gradient centrifugation. Moreover, increasing the stringency of isolation by decreasing the protein : detergent ratio caused an enrichment of the GABAB receptor in raft fractions. In contrast, depletion of cholesterol from cerebellar membranes by either saponin or methyl‐β‐cyclodextrin treatment, which solubilize known raft markers, also increased the solubility of the GABAB receptor. These properties are all consistent with an association of the GABAB receptor with lipid raft microdomains.