Association of turkey erythrocyte beta-adrenoceptors with a specific lipid component.
We have recently reported that the highly potent beta-adrenergic affinity label [125I]bromoacetylamino cyanopindolol ([125I]BAM-CYP) irreversibly blocks the turkey erythrocyte beta-adrenoceptor binding site by combining with a receptor-associated non-protein component. In this communication, we report: lipid labelling is inhibited by beta 1-adrenergic ligands with the potency ratio and stereospecificity characteristic for the turkey erythrocyte beta 1-adrenoceptor; the tagged component is a glycolipid, probably a ganglioside; [125I]BAM-CYP-blocked receptor, after solubilization in deoxycholate, can be separated from the [125I]BAM-CYP-glycolipid with restoration of the binding capacity of the beta 1-adrenoceptor protein; the tightly associated [125I]BAM-CYP-labelled glycolipid can be displaced by a glycolipid mixture extracted from turkey erythrocyte membranes but not by bovine brain gangliosides, when the blocked receptor is solubilized in digitonin. This is the first direct demonstration that a receptor protein is associated with a specific membrane lipid. The possibility that glycolipids play a role in receptor-mediated signal transduction is discussed in view of these findings and in view of data from the literature.
D000345:Affinity Labels / Q000494:pharmacology*; D000818:Animals; D004910:Erythrocyte Membrane / Q000378:metabolism*; D007700:Kinetics; D008563:Membrane Lipids / Q000097:blood*; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D014422:Turkeys
D000345:Affinity Labels; D008563:Membrane Lipids; D011943:Receptors, Adrenergic, beta; C044136:N-(bromoacetylamino)cyanopindolol; D010869:Pindolol