Involvement of CCAAT/enhancer-binding protein in regulation of the rat serine : pyruvate/alanine : glyoxylate aminotransferase gene expression

In the rat liver, transcription of the serine:pyruvate/alanine:glyoxylate a minotransferase (SPT/AGT) gene occurs from two sites, +1 and +66, in exon 1 , resulting in the formation of two mRNAs, one for a precursor of mitochond rial SPT/AGT and the other for peroxisomal SPT/AGT, respectively. In this s tudy, we attempted to characterize the downstream promoter responsible for generation of peroxisomal SPT/AGT. The minimal downstream promoter was conf ined to the +21-+90 region. We demonstrated that C/EBP alpha and C/EBP beta bound around the downstream start site (+66) contribute to the promoter ac tivity. The downstream promoter activity is also regulated positively by a short inverted repeat, located 20-30 bp upstream of the downstream start si te, through a protein factor(s) bound to this region. On the other hand, th e sequence just downstream of the start site may negatively regulate the pr omoter activity. (C) 2001 Published by Elsevier Science B.V. on behalf of t he Federation of European Biochemical Societies.