Aflatoxin B1 alters protein phosphorylation in rat livers

A study was conducted on the effect of aflatoxin B1 on protein phosphorylation in rat livers by incubation of soluble and insoluble cell fractions with [gamma 32P] ATP. SDS-polyacrylamide gel electrophoresis indicated that a total of eight rat liver phosphoproteins were affected during a feeding period of 36 weeks on a carcinogenic aflatoxin B1-containing diet compared to the phosphoprotein patterns obtained from the livers of rats on a normal noncarcinogenic diet. The appearance of only two of these phosphoproteins were cAMP dependent. DEAE-cellulose chromatography employed to separate the different histone kinase activities in soluble rat liver cell fractions, showed that the specific activity of histone kinase I activity was increased but its total activity decreased while the histone kinase II activity stayed unchanged for rats submitted to the aflatoxin B1-containing diet compared to those on the normal noncarcinogenic diet.