Open AccessEffects of Cyclic AMP and Fluoride on Phosphorylation of Ribosomal Protein S6 and on Protein Synthesis in Rabbit Reticulocytes
Author(s) -
FLOYD Georgia A.,
TRAUGH Jolinda A.
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb06331.x
Subject(s) - ribosomal protein s6 , phosphorylation , sodium fluoride , protein biosynthesis , biochemistry , xanthine , phosphate , ribosomal protein , biology , protein phosphorylation , ribosomal rna , microbiology and biotechnology , fluoride , chemistry , ribosome , protein kinase a , rna , enzyme , gene , inorganic chemistry
The effects of N 6 , O 2 ‐dibutyryl‐adenosine 3′, 5′‐monophosphate (Bt 2 cAMP) and sodium fluoride on the phosphorylation of ribosomal protein S6 and on protein synthesis were examined. Rabbit reticulocytes were incubated in a nutritional medium containing 32 P i in the presence and absence of Bt 2 cAMP (1 mM) and 3‐isobutyl‐1‐methyl‐xanthine (1 mM). In the control cells, four phosphorylated derivatives of S6 were observed, with most of the radioactivity in the monophosphorylated form. Upon addition of cyclic nucleotide, a twofold increase in the phosphorylation of ribosomal protein S6 was observed. This was accompanied by an increase of radioactive phosphate in the diphosphorylated derivative. No alteration in protein synthesis was observed upon addition of cAMP and analogues of cAMP in conjunction with 3‐isobutyl‐1‐methyl‐xanthine or theophylline. The effects of sodium fluoride on phosphorylation of S6 and on protein synthesis were examined also. At 5 mM sodium fluoride, protein synthesis was inhibited by 85%. A 2. 5‐fold increase in the phosphorylation of ribosomal protein S6 was observed with an accumulation of 32 P i in the diphosphorylated, triphosphorylated and tetraphosphorylated derivatives. Inhibition of protein synthesis coincided with an increase in the more highly phasphorylated derivatives, whereas an increase of radioactive phosphate in the diphosphorylated derivative could not be correlated with an alteration in globin synthesis.