α-Bungarotoxin Receptor Subtypes

We used anti-α7 and anti-α8 subunit specific antibodies to study a-bungarotoxin (α-BTX) receptors at different developmental stages in chick optic lobe and retina. We found that only the α7 and α7-α8 subtypes are present at all developmental stages in chick optic lobe, whereas in addition to these two subtypes, chick retina contains an α8 subtype representing 50% of all α-BTX receptors at 1 day post hatching. By using an immunoaffinity column, we purified these subtypes and studied their biochemical and functional properties by reconstituting them in planar lipid bilayer. The a7 and α7–α8 receptor subtypes are made up of two subunits: a 57000 dalton subunit which binds α-BTX, and a 52000 dalton subunit whose function and structure is unknown. The three subtypes differ in pharmacological and biophysical properties.