Expression and sequence analysis of the mouse adenine nucleotide translocase 1 and 2 genes

Only two isoforms of the adenine nucleotide translocase (Ant) protein have been identified in mouse, as opposed to the three in humans. To determine whether the homologous mouse and human proteins share similar patterns of expression, Northern and Western analyses were performed on several mouse tissues. Mouse Ant1 is expressed at high levels in skeletal muscle and heart, similar to human ANT1. Mouse Ant2 is strongly expressed in all tissues but muscle, in marked contrast to human ANT2. To investigate the molecular basis of these differences, we cloned and sequenced the genomic loci of mouse Ant1 and Ant2, and compared them to the three human ANT loci. The mouse and human ANT1 and ANT2 genes showed substantial homology starting about 300 base pairs (bp) 5′ to the coding region and continuing through the 3′ untranslated region (UTR). Repeats constituted 32% of 15 kb of Ant1 sequence and 36% of the 27 kb of Ant2 sequence and included SINEs, LINEs and LTR elements. The core promoters of the mouse and human ANT1 and ANT2 genes are very similar. However, the mouse Ant1 gene lacks the upstream OXBOX and REBOX elements found in human ANT1 genes, thought to be important for muscle-specific expression. The mouse Ant2 gene, like human ANT2, has an upstream GRBOX, yet this element is not associated with suppression of transcription, as hypothesized for human ANT2. These discrepancies indicate that additional studies will be required to fully understand the transcriptional regulation of both Ant1 and Ant2.