Isolation and characterization of a Chinese hamster ovary cell mutant which accumulates UDP glucuronic acid and requires uridine for growth

The isolation and characterization of a new pyrimidine requiring mutant of Chinese hamster ovary cells (CHO‐KI, pro) is described. This mutant (P192) shows an absolute requirement for uridine for growth but is fully capable of pyrimidine nucleotide synthesis. P192 cells accumulate exceedingly large amounts of a compound identified by a variety of chromatographic, chemical, and labelling criteria as UDP glucuronic acid (UDPglcUA). This compound comprises approximately 60% of the acid‐soluble nucleotides of P192 cells. Possible genetic mechanisms leading to the phenotype of P192 are examined, and the role of UDPglcUA in cellular metabolism is discussed.