Regulation of De Novo Purine Biosynthesis in Chinese Hamster Cells

Abstract

It has been proposed that in mammalian cells (1), as in the case of E. coli (2), de novo purine biosynthesis is controlled by both feedback inhibition by the end products of the pathway and by repression. In procaryotes, repression appears to involve an interaction between a specific nucleotide (ATP or GTP) and a repressor protein binding to the operator region of the early purine genes (2). We have recently isolated a series of PurR⁻ mutants in E. coli, in which repression of the de novo pathway is abolished (3). However such mutants are still subject to feedback inhibition.