Receptors on phaeochromocytoma cells for two members of the PP-fold family — NPY and PP

Pancreatic polypeptide (PP) and neuropeptide Y (NPY) belong to a family of regulatory peptides which hold a distinct tertiary structure, the PP-fold, even in dilute aqueous solution. High-affinity receptors, specific for both PP and NPY, are described on the rat phaeochromocytoma cell line, PC-12. The binding of [ 125I-Tyr 36]PP to PC-12 cells was inhibited by concentrations of unlabeled PP which correspond to physiological concentrations of the hormone, 10 −11-10 −9 mol/1. The affinity of the receptor for the neuropeptide, NPY, was 10 2-times lower than that of the PP receptor. C-terminal fragments of both PP (PP 24–36) and NPY (NPY 13–36) were between 10 2 - and 10 3-times less potent in displacing the radiolabeled 36-amino-acid peptides from their respective receptors. It is concluded that PC-12 cells are suited for structure-function studies of the PP-fold peptides and studies on the cellular events following cellular binding of PP-fold peptides.