Affinity isolation of imidazoline binding proteins from rat brain using 5-amino-efaroxan as a ligand

We have employed an amino derivative of the imidazoline ligand, efaroxan, t o isolate imidazoline binding proteins from solubilised extracts of rat bra in, by affinity chromatography. A number of proteins were specifically reta ined on the affinity column and one of these was immunoreactive with an ant iserum raised against the ion conducting pore component of the ATP-sensitiv e potassium channel. Patch clamp experiments confirmed that, like its paren t compound, amino-efaroxan blocks ATP-sensitive potassium channels in human pancreatic beta-cells and can stimulate the insulin secretion from these c ells, The results reveal that a member of the ion conducting pore component family is strongly associated with imidazoline binding proteins in brain a nd in the endocrine pancreas. (C) 1999 Federation of European Biochemical S ocieties.