pubmed-article:1782219 | pubmed:abstractText | The kinetics of formation of mono-, and diphosphorylated derivatives of ribosomal protein S8 in Tetrahymena starving in the presence of Na+ have been determined, and the phosphoamino acids present in these derivatives have been identified. The mono-phosphorylated product, S8', contains only phosphoserine, and behaves kinetically as the precursor of the diphosphorylated product S8" which contains phosphoserine, and phosphothreonine. Tryptic digestion release a single major phosphoserine containing peptide from both S8' and S8", and a single phosphothreonine containing peptide from S8". | lld:pubmed |