title: Difference in phosphorylation of two factors stimulating RNA polymerase II of Ehrlich ascites tumor cells.
abstract: The structures of two protein factors, S-II and S-II', that specifically stimulate RNA polymerase II from Ehrlich ascites tumor cells were compared. The two proteins behaved differently on CM-cellulose chromatography and on isoelectric focusing, although they were shown to have common antigenicity. The following findings strongly suggest that S-II and S-II' have the same primary structure, but that S-II' is more extensively phosphorylated than S-II: (1)S-II an S-II' gave identical peptide maps when digested with various proteases. (2) S-II' that had been treated with alkaline phosphatases had the same mobility on sodium dodecyl sulfate-polyacrylamide gel as S-II, indicating that it could be converted to S-II by hydrolysis of its phosphate residues. (3) S-II' was phosphorylated more than S-II when Ehrlich ascites tumor cells were labeled in vivo with [32P]orthophosphate.
mesh_terms: D000469:Alkaline Phosphatase; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004789:Enzyme Activation; D051379:Mice; D009363:Neoplasm Proteins / Q000302:isolation & purification* / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis; D010769:Phosphothreonine / Q000032:analysis; D012319:RNA Polymerase II / Q000378:metabolism*; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; D014357:Trypsin
chemical_list: D009363:Neoplasm Proteins; D010446:Peptide Fragments; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; C018648:transcription factor S-II; D010769:Phosphothreonine; D010768:Phosphoserine; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases; D000469:Alkaline Phosphatase; D014357:Trypsin