Chemicon's CRF1 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 CRF1 interactions with its ligands. The membrane preparations exhibit a Kd of 1 nM for [125I]-sauvagine. With 2.5 μg/well CRF1 Membrane Prep and 0.5 nM [125I]-sauvagine, a greater than 12-fold signal-to-background ratio is obtained.