Solubilization of high affinity peptide-YY receptors from porcine brain.

We have previously characterized peptide-YY (PYY) receptors in porcine hippocampal membranes. We demonstrate here that brain PYY receptors can be extracted in the active state using digitonin. Among several detergents tested for their suitability to extract active PYY receptors, digitonin gave the most favorable results, as judged by specific binding of [125I]PYY to the solubilized receptors. The binding of [125I]PYY to digitonin extract was dependent on incubation time, temperature, and protein and magnesium ion concentrations and had a pH optimum of 6-7. Solubilized PYY receptors maintained the rank order of potencies for various related peptides and PYY fragments characteristic of the membrane PYY receptor: PYY greater than neuropeptide Y (NPY) much much greater than avian and porcine pancreatic polypeptide, and PYY greater than PYY-(22-36) much much greater than PYY-(1-22) and PYY-(22-28), respectively. Scatchard analyses of competitive binding data indicated the presence of two classes of binding sit...