Purification by affinity chromatography and immunological characterization of a 110kDa component of the chick oviduct progesterone receptor

Abstract

A 110 kDa [kilodalton] component of the chick oviduct progesterone receptor (PR) was purified to homogeneity according to electrophoretic criteria and specific activity (assuming 1 progestagen-binding site per 110 kDa). The procedure involved affinity chromatography of 0.3 M-KCl-prepared cytosol, followed by DEAE-Sephacel chromatography (elution at 0.2 M-KCl). The final yield was about 12% in terms of binding activity. Properties of the 110 kDa component indicate that it is identical with the B subunit described previously [Stokes radius .apprx. 6.1 nm; sedimentation coefficient, (s20,w) .apprx. 4S; frictional ratio .apprx. 1.77]. It reacted with the IgG-G3 polyclonal antibody, but not with BF4 monoclonal antibody raised against the 8S molybdate-stabilized chick oviduct PR and reacting with its 90 kDa component. Another progesterone-binding component, corresponding to the A subunit, also previously described, was eluted from the DEAE-Sephacel column at .apprx. 0.08 M-KCl, and contained a peptide of molecular mass .apprx. 75-80 kDa, which had s20,w .apprx. 4S in a sucrose gradient. This component was also recognized by IgG-G3, but not by BF4; it was very unstable in terms of hormone-binding activity.