Further characterization of the dioxin receptor in the rat deciduoma

The rat deciduoma cytosol contains a protein which binds radio-labeled dioxin and sediments as an 8-9 S entity on 10-40 per cent (w/v) sucrose density gradients. Incubation of cytosol with [3H]-TCDD at 37 degrees C for ten minutes shifted the sedimentation coefficient from 8-9 S to 4-5 S, whereas incubation of cytosol at room temperature for 30 minutes has no effect on the S value. At high concentrations of [3H]-TCDD the dioxin receptor complex tends to aggregate. Cytosol eluted with 0.25 M KCl from a DEAE cellulose column and complexed with [3H]-TCDD sedimented at 9S in low ionic strength buffer, but sedimented slower (5S) in the presence of 0.4 M KCl in the buffer. The effect of salt and temperature on the sedimentation behavior is compared with that of steroid receptors. The usage of DEAE cellulose column chromatography in purification of the receptor complex is also discussed.