Hyperplastic nodules and hepatocarcinomas were produced in rat liver by 2-acetylaminofluorene-containing diet. The homogenates and isolated microsomes were analyzed for the content of
lipid intermediates and glycosylation reactions. The
dolichol content of hyperplastic nodules increases four times in the homogenate and six times in the microsomes. In developed hepatocarcinoma, the amount of
dolichol was doubled. Concerning the distribution pattern of the
polyprenols, there is a change in the relative amounts of
dolichols with 18 and 19 residues. In contrast to the free alcohol,
dolichyl phosphate was greatly decreased in nodules, a finding which might be explained by a decreased
dolichol kinase and an increased
dolichol monophosphatase activity. The percentage of total phosphorylated
dolichol was related to the glycosylating capacity. In microsomes, mitochondria, and homogenate from normal liver and in homogenate from hyperplastic liver nodules, the percentages of
dolichyl phosphate were 23, 2, 16, and 4, respectively. At maximal glycosylation in vitro, only part of the total
dolichyl phosphate was glycosylated.
Dolichol-mediated protein glycosylation exhibited a general decrease in the microsomes from nodules and
cancer tissue; it is suggested that the main cause of the decrease is a shortage of the available
dolichyl phosphate which is rate limiting and which also contributes to the synthesis of the modified
oligosaccharide chain.