Involvement of folic acid in the synthesis of membrane-associated nucleotide sugars by normal and transformed mouse fibroblasts

A plasma-membrane-containing fraction isolated from Swiss mouse (3T3) fibroblasts was found to contain uridine di-phosphate sugars and methyl-uridine diphosphate (mUDP) sugars. The synthesis of the mUDP sugars by membrane preparations of normal and transformed 3T3 cells occurred from the intrinsic membrane uridine-diphosphate sugars + methylene-tetrahydrofolic acid. Compared to the normal 3T3 cells, the synthesis of mUDP sugars by the transformed 3T3 cells was reduced by 49%. It is proposed that the plasma-membrane-associated mUDP sugars may be essential for normal cell growth.