title: Modulation of phosphorylation of a 30-kD polyribosomal protein (pp30) by ACTH and spermine: comparison with modulation of brain protein synthesis.
abstract: Gel electrophoretic separation of proteins phosphorylated in a postmitochondrial supernatant fraction of brain in the presence of spermine or adrenocorticotropin (ACTH) indicated modulation in only one region (30 kD) of the gel. The 30-kD (pp30) protein together with enzyme activity catalyzing its phosphorylation and sensitivity of the phosphorylation to spermine and ACTH were retained in a free polyribosomal fraction of this extract. ACTH(11-24) inhibited phosphorylation at all the spermine or Mg2+ concentrations tested. Structure-activity studies revealed that the inhibitory activity within ACTH(1-24) resides in the sequences ACTH(11-24), (5-18, 17Lys, 18Lys)-NH2, (15-24), (7-16)-NH2, and (1-16)-NH2 and can also be found in certain polylysine fragments. Phosphorylation under conditions suitable for measuring protein synthesis revealed only one phosphoprotein (pp30), sensitive to both ACTH(15-24) and spermine. The possibility of a relationship between modulation of pp30 phosphorylation and modulation of brain cell-free protein synthesis is discussed in relation to the effects of ACTH, spermine, and Mg2+.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011107:Polylysine / Q000494:pharmacology; D051381:Rats; D012269:Ribosomal Proteins / Q000378:metabolism*; D013096:Spermine / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D012269:Ribosomal Proteins; D011107:Polylysine; D013096:Spermine; D000324:Adrenocorticotropic Hormone; D008274:Magnesium