We report the isolation and sequence of the Schizosaccharomyces pombe
ade4 gene which encodes the glutamine phosphoribosylpyrophosphate amid
otransferase, the first enzyme of the purine nucleotide de-novo biosyn
thetic pathway. The enzyme contains 533 amino acids and its sequence e
xhibits homologies to the corresponding enzymes of Saccharomyces cerev
isiae, Escherichia coli, Bacillus subtilis, chicken, rat, and human. I
n contrast to the situation in S. cerevisiae, adenine does not repress
ade4 expression at the mRNA level and also other nutritional signals
seem not to affect its expression.