Solubilization of active brain alpha 1-adrenoceptors by a zwitterionic detergent.
Solubilization of rat brain alpha 1-adrenoceptors was performed by treatment with 6 mM CHAPS (3-[(3-cholamidopropyl)dimethylammonio] - 1 - propanesulfonate). The alpha 1-adrenoceptor antagonist [3H]prazosin was shown to bind reversibly and specifically to the soluble extract obtained after centrifugation at 150,000 X g for 1 h. Separation of the soluble [3H]prazosin-bound complexes was performed by the polyethylene glycol precipitation technique followed by filtration. A Scatchard plot of the concentration-dependent binding curve showed only one class of binding sites, with a high affinity for [3H]prazosin. Affinity of the solubilized receptors for the ligand increased as the CHAPS concentration in the assay medium decreased; the number of binding sites remained unchanged (approximately equal to 70 fmol/mg protein). This corresponds to a 30% recovery of original membrane sites. The solubilized receptors presented the same characteristics of specificity and stereospecificity as membrane alpha 1-adrenoceptors. Moreover, 150 mM NaCl was found to modulate the affinity of epinephrine for the [3H]prazosin-bound soluble complex, as previously described for membrane preparations. Thus, CHAPS appears to be a suitable detergent for solubilizing rat brain alpha 1-adrenoceptors and preserving their functional activities.
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000302:isolation & purification*; D011942:Receptors, Adrenergic, alpha / Q000302:isolation & purification* / Q000378:metabolism; D012995:Solubility
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011224:Prazosin; D004837:Epinephrine