Solubilization of mu-opioid receptors enriched from bovine brain membranes

Solubilization is the most critical step in the purification of opioid receptors as these proteins are highly sensitive to detergents and get inactivated even with very mild detergents. Membranes enriched with micro-opioid receptors from bovine corpus striatum were solubilized by various methods to obtain the active soluble receptor suitable for affinity purification. Solubilization by digitonin resulted in marginal yields. CHAPS in presence of NaCl could extract active receptor into the solution. The detergent and NaCl were removed by either polyethylene glycol precipitation or by desalting on Sephadex G50. The polyethylene glycol precipitation resulted in the formation of liposomes into which the receptor protein was incorporated. Liposome formation was not observed in desalting method and the recovery of the receptor was partial.