title: Solubilization and characterization of the beta-bungarotoxin-binding protein of chick brain membranes.
abstract: The previously characterized ( Rehm , H., and Betz, H. (1982) J. Biol. Chem. 257, 10015-10022) neuronal binding protein for the presynaptic neurotoxin beta-bungarotoxin (beta-BuTx) was solubilized from synaptic membrane fractions of chick brain using the nonionic detergent Triton X-100. 125I-beta-BuTx bound to the solubilized protein with a dissociation constant (KD) of 1.9 +/- 0.1 nM. This binding of 125I-beta-BuTx was Ca2+-dependent and pharmacologically specific. From different basic proteins tested, only unlabeled beta-BuTx and its antagonist dendrotoxin inhibited 125I-beta-BuTx binding. Potassium ions were required during solubilization and binding in order to detect 125I-beta-BuTx-binding activity. Sedimentation in sucrose/H2O and sucrose/D2O gradients and gel exclusion chromatography on Sepharose 6B indicated a s20,w of 12.8 +/- 0.6 S and a Stokes radius of 8.6 +/- 0.2 nm for the solubilized beta-BuTx-binding component. From these data, the protein molecular weight of the beta-BuTx binding site was calculated to be 431,000 +/- 45,000.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002038:Bungarotoxins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000302:isolation & purification*; D002645:Chickens; D004546:Elapid Venoms / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism; D008433:Mathematics; D008566:Membranes / Q000032:analysis; D017830:Octoxynol; D011092:Polyethylene Glycols; D011188:Potassium / Q000494:pharmacology; D012995:Solubility; D013324:Strontium / Q000378:metabolism
chemical_list: D002038:Bungarotoxins; D002352:Carrier Proteins; D004546:Elapid Venoms; C041451:beta-bungarotoxin binding protein, rat; D011092:Polyethylene Glycols; C020273:dendrotoxin; D017830:Octoxynol; D008274:Magnesium; D011188:Potassium; D002118:Calcium; D013324:Strontium