MOLECULAR-CLONING AND EXPRESSION OF A RAT CDNA-ENCODING 5-AMINOIMIDAZOLE-4-CARBOXAMIDE RIBONUCLEOTIDE FORMYLTRANSFERASE IMP CYCLOHYDROLASE

The cDNA of a 5-aminoimidazole-4-carboxamide ribonucleotide formyltran sferase/IMP cyclohydrolase (AICARFT/IMPCHase) was isolated from rat li ver RNA by reverse transcription and the polymerase chain reaction (PC R). The rat AICARFT/IMPCHase cDNA included 1928 bp containing a coding region of 1779 bp for a 592-amino acid polypeptide (M-r = 64 200). Ra t and human AICARFT/IMPCHase cDNAs show 84 and 91% homology at the nuc leotide and amino acid sequence level, respectively. The protein produ ced by the rat cDNA using pET-expression system catalysed the penultim ate and final steps of de novo purine biosynthesis. Northern analysis identified a 2.8-kb AICARFT/IMPCHase mRNA and the level of the AICARFT /IMPCHase transcripts increased markedly at 24 h after partial (70%) h epatectomy. (C) 1997 Elsevier Science B.V.