title: Estradiol and phorbol ester cause phosphorylation of serine 118 in the human estrogen receptor.
abstract: Serine 118 is definitively identified as a major site of phosphorylation in the human estrogen receptor expressed in COS-1 cells treated with estradiol or phorbol ester. At least 30% of the estrogen receptor appears to be phosphorylated on serine 118 after treatment with estradiol or phorbol ester. Human estrogen receptor was expressed in COS-1 cells and labeled in vivo with [32P]orthophosphate in the presence of estradiol or phorbol ester. Immunopurified receptor was digested with cyanogen bromide. The most heavily labeled peptide (7 kilodaltons) was identified as amino acids 110-174 by microsequencing. Manual Edman degradation released a major portion of the 32P-label in the peptide at serine 118. A mutant with serine 118 replaced by alanine (S118A) had 80% less 32P-label in the 7 kilodalton peptide. Estrogen receptor labeled in vivo with [32P]-orthophosphate in the presence of estradiol or phorbol ester migrates electrophoretically as a doublet. The major difference between the bands is phosphorylation of serine 118 in the upshifted band. The mutant S118A does not show an upshifted band. Labeling of the estrogen receptor with [35S]methionine indicates that > or = 30% of the receptor is upshifted and suggests that > or = 30% of the receptor is phosphorylated on serine 118.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003488:Cyanogen Bromide / Q000737:chemistry; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010449:Peptide Mapping; D010768:Phosphoserine / Q000737:chemistry / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D011960:Receptors, Estrogen / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D011994:Recombinant Proteins; D010768:Phosphoserine; D004958:Estradiol; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D003488:Cyanogen Bromide