The calcitonin family of peptides, which includes calcitonin, two calcitonin-related gene peptides (CGRPs), adrenomedullin, and amylin, share a disulfide-bonded loop, an amphipathic a-helix, and an amidated C-terminus. The peptides influence a variety of physiological effects, including vascular tone, food intake and bone metabolism. The biological effects of the peptides are mediated by two class B GPCRs, the CT and CL receptors (Poyner et al., 2002). The pharmacology of the CT and CL receptors is strongly influenced by their association with a family of three receptor activity modifying proteins (RAMPs), which are 14-17 kD single pass transmembrane proteins. When expressed with no modifying proteins, the CT receptor binds with high affinity only to calcitonin. The CT receptor in complex with RAMP proteins binds amylin with high affinity, as well as calcitonin and aCGRP; the CT receptor complexes with RAMP1, RAMP2 and RAMP3 are termed AMY1, AMY2 and AMY3. Amylin (also known as islet amyloid polypeptide) is produced by pancreatic beta cells. Experiments with amylin-deficient mice indicate that amylin and its receptors control food intake and pain perception. Pramlintide, a synthetic analog of amylin, is used clinically for glucose control in diabetics. AMY1 membrane preparations are crude membrane preparations made from our proprietary stable recombinant cell lines to ensure high-level of GPCR surface expression; thus, they are ideal HTS tools for screening of antagonists of AMY1 interactions with hCGRP. The membrane preparations exhibit a Kd of 0.29 nM for [125I]-hCGRP. With 10 mg/well of AMY1 Membrane Prep and 0.2 nM [125I]-hCGRP, a greater than 10-fold signal-to-background ratio was obtained.