Thyrotropin-stimulated phosphorylation of high mobility group protein 14 in vivo at the site catalyzed by cyclic nucleotide-dependent protein kinases in vitro.
Thyrotropin (TSH) treatment of bovine thyroid slices increased 32P-labeling of chromosomal high mobility group 14 (HMG) protein approximately 2-fold. Analogs of cAMP, but not cGMP, also enhanced phosphorylation of HMG 14. The sites of phosphorylation were analyzed by partial acid hydrolysis and by two-dimensional mapping of tryptic digests of 32P-labeled HMG 14 which was purified from control and TSH-treated thyroid tissue. TSH treatment enhanced phosphorylation at serine residues in four prominent tryptic phosphopeptides which were identical with those derived from HMG 14 phosphorylated in vitro with cAMP- and cGMP-dependent protein kinases. The four tryptic phosphopeptides contain serine 6, the major site of in vitro phosphorylation catalyzed by cyclic nucleotide-dependent protein kinases (Walton, G. M., Spiess, J., and Gill, G. N. (1982) J. Biol. Chem. 257, 4661-4668). TSH did not affect phosphorylation of serine 24, a minor site of phosphorylation in vitro. These studies suggest that TSH-stimulated phosphorylation of HMG 14 is catalyzed by cAMP-dependent protein kinase.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D006609:High Mobility Group Proteins; D066298:In Vitro Techniques; D011494:Protein Kinases / Q000378:metabolism*; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013972:Thyrotropin / Q000494:pharmacology*
D000596:Amino Acids; D002868:Chromosomal Proteins, Non-Histone; D006609:High Mobility Group Proteins; D013972:Thyrotropin; D000242:Cyclic AMP; D011494:Protein Kinases; D006152:Cyclic GMP