Multiple promoters direct the tissue-specific expression of rat mitochondrial glycerol-3-phosphate dehydrogenase

The mitochondrial FAD-dependent glycerol-3-phosphate dehydrogenase (mGPDH) is an essential component of the glycerol phosphate shuttle which transfers reduction equivalents from the cytoplasm into the mitochondria. We analyzed the distribution of different exon 1-containing transcripts by RT-PCR in various tissues in vivo. Exon la was predominantly expressed in brain, brown adipose tissue and pancreas, exon Ib was ubiquitously expressed, and exon Ic was exclusively expressed in testis. In transient transfection assays the ubiquitous promoter B showed a detectable activity, whereas promoters A and C were completely silent. A deletion mutational analysis located the basal promoter B activity to a 316 bp core sequence upstream of the transcription start site.