Separation and characterization of 7 and 9 S forms of rat liver aryl hydrocarbon receptor

Two forms of rat liver aryl hydrocarbon receptor were separated by chromatography on DEAE-cellulose in the presence of molybdate. After labeling for 2 h at 0 degrees C, the receptor separated on the DEAE column into a flow-through peak (peak I) and a peak eluting at 80 mM KCl (peak II). It had been reported previously that exposure to high salt in the presence of molybdate caused the appearance of both 9 and 5-6 S receptor forms. After confirming this, I examined the relationship of the peak I and peak II receptors to these receptor forms. In high salt buffer containing molybdate, the peak I receptor sedimented in the 5-6 S region and the peak II receptor at 9 S. High salt buffer lacking molybdate converted both peak I and peak II receptors to forms sedimenting in the 5-6 S region. In low salt buffer containing molybdate, the peak I receptor sedimented at slightly more than 7 S and the peak II receptor at 9-10 S. Thus, the peak II receptor could be stabilized by molybdate as a 9 S form, and the peak I receptor was converted by high salt from a 7 to a 5-6 S form, despite the presence of molybdate. Most of the peak I receptor bound to a DNA-cellulose column and was eluted by high salt. The peak II receptor showed very little DNA binding.