Studies on the activities of some methyltransferases in the livers and tumor cells from tumor-bearing mice

The activities of $\text{S}$-adenosylmethionine synthetase isozymes and some methyltransferases have been measured in liver and tumor cells of tumor-bearing mice. Following intraperitoneal transplantation of Ehrlich ascites tumor cells into mice, the activity of the β-form of the synthetase isozymes markedly increased, whereas that of the α-form did not increase so much, and the activity of tRNA methyltransferases increased gradually, while that of phospholipid, glycine and guanidoacetate methyltransferases did not. It was shown that tumor cells have only the γ-form of the synthetase and that the activity of tRNA methyltransferases in the tumor cells was very high, while that of other methyltransferases was not detectable.