Xenopus adenine nucleotide translocase mRNA exhibits specific and dynamic patterns of expression during development

We report the isolation and characterization of the Xenopus homolog to huma n T1 ANT (adenine nucleotide translocase). The 1290-nucleotide sequence con tains initiation and termination signals, and encodes a conceptual protein of 298 amino acids. The sequence shares high amino acid identity with the m ammalian adenine translocases. The transcript is present in unfertilized eg gs, and it is expressed at higher levels during formation of the antero-pos terior dorsal axis in embryos. Although low levels are expressed constituti vely except in endodermal cells, adenine nucleotide translocase (ANT) expre ssion is dynamically regulated during neurulation. At this stage, expressio n in ectoderm rapidly diminishes as the neural folds form, and then ANT exp ression increases slightly in mesoderm. At the culmination of neurulation, the neural tube briefly expresses ANT, and thereafter its expression predom inates in the somitic mesoderm and also the chordoneural hinge. In addition , ANT expression is particularly high in the prosencephalon, the mesencepha lon, the branchial arches, eye, and the otic vesicle. Treatment of embryos with retinoic acid has the effect of diminishing constitutive expression of ANT, but microinjection studies demonstrate that immediate and local repre ssion cannot be induced in dorsal structures.