Characterization of a monoclonal antibody to the rat liver glucocorticoid receptor.

The rat liver glucocorticoid receptor was partially purified and used to immunize a BALB/c mouse whose splenic lymphocytes were fused with the nonsecreting myeloma cell line P3-AgX-653. The fusion products were selected in HAT (hypoxanthine, aminopterine, and thymidine) medium and a stable antibody-producing clone designated BuGR1 obtained from 1 of 81 positive wells. Immunological specificity for the receptor was confirmed by sucrose density gradient analysis when the sedimentation constant of the specifically labeled receptor was altered by reaction with the antibody and by Western blot analysis, which showed that the BuGR1 antibody detected a single band with a mobility (mol wt, approximately 95,000) identical to that of the [3H]dexamethasone 21-mesylate-labeled rat glucocorticoid receptor. Similar sucrose gradient and Western blot experiments showed that the BuGR1 antibody reacted with the mouse glucocorticoid receptor. BuGR1 is a stable hybridoma producing an antibody which detects loci common to both rat and mouse glucocorticoid receptors.