Purification of a prolactin receptor.

A prolactin receptor was purified from a solubilized preparation of mouse microsomal membranes by affinity chromatography. The receptors were solubilized with the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate)(Chaps) a zwitterionic derivative of cholic acid. The affinity gel was prepared by coupling ovine prolactin to CH-Sepharose 4B. After extensive elution of the nonspecifically adsorbed proteins, the receptors were eluted with 4 M urea/1 M NaCl/0.5% Chaps followed by 5 M MgCl2/0.5% Chaps. The eluted receptor appeared on NaDodSO4/polyacrylamide gels as a single major band of Mr 37,000. The purified receptor retained its specificity for lactogenic hormones and binds 125I-labeled ovine prolactin with a Ka of 2-6 X 10(9) M-1.