Human R1 subunit of ribonucleotide reductase (RRM1): 5' flanking region of the gene.

Ribonucleotide reductase is essential, in dividing cells, for the production of deoxyribonucleotides prior to DNA synthesis in S phase. Neither of its two subunits (R1 and R2) are detectable in quiescent cells. In cycling cells, RRM1 mRNA and R1 protein are present throughout the cell cycle. A fragment of the human cDNA was used to isolate a genomic clone that encompasses the 5' flanking region of human RRM1. Primer extension and PCR experiments were used to define six potential cap sites. The immediate upstream region does not have a TATA box and is not GC-rich. A 1.9-kb fragment (-1670 to +208) was able to direct transcription of a reporter gene in a transient expression system. Understanding the mechanisms regulating expression of this gene will provide insight into the processes involved in cell cycling and may be of particular importance in understanding the deregulated growth of transformed cells.