Regulation of GABA receptor binding to synaptic plasma membrane of rat cerebral cortex: the role of endogenous phospholipids.
Triton X-100 treatments produced an extensive depletion of proteins and phospholipids and a marked increase of [3H] GABA binding on synaptic plasma membranes (SPM). Maximal [3H]GABA binding was obtained with three Triton X-100 treatments (+ 174% with respect to control). Phospholipase C, which removes only the phospholipid polar head, induces a 40% increase of [3H]GABA binding only after treatments resulting in extensive protein depletion. In reconstitution experiments phosphatidylethanolamine, the largest phospholipid removed, induced a 30-35% inhibition of [3H]GABA binding in Triton X-100 treated membranes; in contrast phosphatidylserine and phosphatidylcholine did not produce significant changes. The reconstitution of phospholipase C-treated SPM preparations with exogenous phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine or phosphoethanolamine and 1,2-dipalmitoylglycerol, products of phospholipase C activity, did not yield significant changes. This evidence, which argues against a direct role of phospholipids on the regulation of GABA binding, should, however, suggest that the GABA binding component of the receptor site is a lipoprotein or a lipid-depending protein.
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008563:Membrane Lipids / Q000502:physiology*; D017830:Octoxynol; D010743:Phospholipids / Q000494:pharmacology / Q000502:physiology*; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011963:Receptors, GABA-A; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D003902:Detergents; D008563:Membrane Lipids; D010743:Phospholipids; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D011092:Polyethylene Glycols; D005680:gamma-Aminobutyric Acid; D017830:Octoxynol; D010738:Type C Phospholipases