Purification of oestradiol receptor from human uterus by affinity chromotrgraphy

The oestrogen receptor from human myometrium has been extensively purified by affinity chromatography and isoelectric focusing. The latter step is necessary to remove contaminating sex-steroid-binding globulin. The unpurified 3.7-S cytoplasmic receptor has a molecular weight of 41,000, a Stokes radius of 27.0 A and a frictional ratio (f/f0) of 1.19; the KD (4 degrees C) for [3H]oestradiol-17 beta was 1.03 X 10(-10) M. After purification, the molecular weight was 30,000, the Stokes radius 23.6 A, frictional ratio 1.15 and isoelectric point 6.15.