title: Localization of phosphorylation sites with respect to the functional domains of the mouse L cell glucocorticoid receptor.
abstract: Digestion of the rat liver glucocorticoid receptor with chymotrypsin results in the generation of a 42-kDa fragment which contains the steroid-binding and DNA-binding domains and the antigenic site for the BuGR anti-glucocorticoid receptor monoclonal antibody, while digestion with trypsin generates a 15-kDa receptor fragment containing only the DNA-binding function and the BuGR epitope (Eisen, L.P., Reichman, M.E., Thompson, E.B., Gametchu, B., Harrison, R. W., and Eisen, H.J. (1985) J. Biol. Chem. 260, 11805-11810). In this paper, glucocorticoid receptor of mouse L cells that were grown in the presence of [32P]orthophosphate was digested with trypsin or chymotrypsin (either before or after immune purification with BuGR antibody) and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, autoradiography, and Western blotting. The receptor is endogenously phosphorylated only on serine residues. Chymotrypsin digestion results in a 32P-labeled 42-kDa receptor fragment which contains steroid-binding, DNA-binding, and BuGR-reactive sites. Trypsin digestion generates a 27-kDa steroid-bound fragment (meroreceptor) which is not labeled with 32P and a 32P-labeled 15-kDa fragment which contains both the DNA-binding domain and the BuGR epitope. We have calculated that there are 4 times as many phosphate residues in the intact receptor than in the 42-kDa chymotrypsin fragment. From examination of 32P-labeled receptor fragments, we have deduced that one phosphate is located between amino acids 398 and 447, a region containing the BuGR epitope and about one-third of the DNA-binding domain, and the remaining three phosphates appear to be clustered just to the amino-terminal side of the BuGR epitope in a region defined by amino acids 313 to 369. Treatment of intact 32P-labeled receptor in cytosol with alkaline phosphatase removes these three phosphates, but it does not remove the phosphate from the DNA-binding-BuGR-reactive fragment and it does not affect the ability of the transformed receptor to bind to DNA-cellulose.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007124:Immunoenzyme Techniques; D007163:Immunosorbent Techniques; D007739:L Cells; D051379:Mice; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D010710:Phosphates; D011965:Receptors, Glucocorticoid; D010768:Phosphoserine; D004247:DNA; D002918:Chymotrypsin; D014357:Trypsin