Hormonally inducible phosphorylation of a nuclear pool of ribosomal protein S6.
Thyrotropin releasing hormone (TRH) and epidermal growth factor induce the rapid phosphorylation of a basic, chromatin-associated protein present in GH4 rat pituitary cells and also found in primary hepatocyte culture. Cell fraction experiments indicate a nucleolar localization for this basic, chromatin-associated protein. The protein has been purified to homogeneity from rat liver and 23 amino acids of its N-terminal sequence determined. There is complete homology between the sequenced portion of the basic, chromatin-associated protein and the N-terminal sequence of rat ribosomal protein S6. In vivo and in vitro phosphorylation, two-dimensional gel analysis and two-dimensional tryptic phosphopeptide mapping support the identity of the basic, chromatin-associated protein and S6. Our experimental data indicate the existence of a nuclear pool of S6 whose phosphorylation is hormone inducible.
Franco
R
R
Eukaryotic Regulatory Biology Program, University of California, San Diego School of Medicine, La Jolla 92093.
Rosenfeld
M G
MG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002458:Cell Fractionation; D002460:Cell Line; D002466:Cell Nucleolus / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D008099:Liver / Q000648:ultrastructure; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000378:metabolism*; D010766:Phosphorylation; D010902:Pituitary Gland / Q000648:ultrastructure; D051381:Rats; D038601:Ribosomal Protein S6; D012269:Ribosomal Proteins / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D014357:Trypsin
D010748:Phosphopeptides; D038601:Ribosomal Protein S6; D012269:Ribosomal Proteins; D013973:Thyrotropin-Releasing Hormone; D004815:Epidermal Growth Factor; D014357:Trypsin; D013755:Tetradecanoylphorbol Acetate