A subpopulation of estrogen receptors are modified by O-linked N-acetylglucosamine.
Estrogen receptors (ER) are ligand-inducible transcription factors regulated by Ser(Thr)-O-phosphorylation. Many transcription factors and eukaryotic RNA polymerase II itself are also dynamically modified by Ser(Thr)-O-linked N-acetylglucosamine moieties (O-GlcNAc). Here we report that subpopulations of murine, bovine, and human estrogen receptors are modified by O-GlcNAc. O-GlcNAc moieties were detected on insect cell-expressed, mouse ER (mER) by probing with bovine milk galactosyltransferase, followed by structural analysis. Wheat germ agglutinin-Sepharose affinity chromatography also readily detected terminal GlcNAc residues on subpopulations of ER purified from calf uterus, from human breast cancer cells (MCF-7), or from mER produced by in vitro translation. These data suggest that greater than 10% of these populations of estrogen receptors bear O-GlcNAc. Site mapping of insect cell expressed mER localized one major site of O-GlcNAc addition to Thr-575, within a PEST region of the carboxyl-terminal F domain. Based upon their relative resistance to both hexosaminidase and to in vitro galactosylation, O-GlcNAc moieties appear to be largely buried on native mER. This dynamic saccharide modification, like phosphorylation, may play a role in modulating the dimerization, stability, or transactivation functions of estrogen receptors.
Jiang
M S
MS
Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Hart
G W
GW
D000117:Acetylglucosamine / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005690:Galactose / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011960:Receptors, Estrogen / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
D011960:Receptors, Estrogen; D000117:Acetylglucosamine; D005690:Galactose