The p53 tumour suppressor protein is phosphorylated at serine 389 by casein kinase II.

摘要: The entire coding sequence of wild-type mouse p53 was expressed in Escherichia coli under control the PL promoter bacteriophage lambda. bacterial protein had identical mobility to from SV3T3 cells on SDS polyacrylamide gels and recognized lysates by three p53-specific monoclonal antibodies, including PAb246 which is specific for p53. Immunoprecipitates were phosphorylated a highly purified preparation rat casein kinase II; stoichiometry incorporation approximately 1 mol phosphate per residue identified phosphopeptide mapping as serine 389, major site phosphorylation vivo. (serine 389) activity detected cells; this co-purified with II phosphocellulose Mono Q columns inhibited heparin. p53-T antigen complex also associated 389 activity. Phosphorylation potently heparin quenched excess unlabelled GTP. data indicate that physiological substrate II, stimulated response mitogens, phosphorylates nuclear oncoproteins, may play role transduction extracellular signals nucleus.