title: Purification of a new protein stimulating RNA polymerase II from Ehrlich ascites tumor cells: comparison with proteins purified before.
abstract: A protein factor named S-I(b) that stimulates the activity of RNA polymerase II was purified from Ehrlich ascites tumors cells. The final preparation gave a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein has a molecular weight of 24,000 and is significantly smaller than S-II and S-II', stimulatory proteins of RNA polymerase II purified previously. However, S-I(b) cross-reacted with antibody against S-II and its peptide map obtained after radio-iodination was identical with that of S-II' (a phosphorylated form of S-II), indicating that S-I(b) and S-II share a common primary structure. S-I(b) is suggested not to be a degradation product of S-II produced during the purification process, and the structural relations between S-II and S-II' are discussed.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000032:analysis*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003168:Complement Fixation Tests; D003429:Cross Reactions; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008297:Male; D051379:Mice; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000032:analysis; D012319:RNA Polymerase II / Q000378:metabolism*; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; D014357:Trypsin / Q000378:metabolism
chemical_list: D009363:Neoplasm Proteins; D010446:Peptide Fragments; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; C018648:transcription factor S-II; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases; D014357:Trypsin