(1)AP-2 enhances Sp1-dependent activation of the growth-regulated human ATP ADP translocator

The mammalian ATP/ADP translocator isoform-2 (ANT2) gene is growth-activate d. Regulation of the gene appears to involve Sp1, as an essential activator , and a suppressor through an Spl core element next to the transcription st art. We show here that the proximal promoter also binds AP-2 strongly and s pecifically to two sites, one of which overlaps the Spl proximal suppressor site. AP-2 binds with an affinity of 10 to 15 fold higher than that of Spl , AP-2 alone does not alter the ANTE promoter activity in transfected SL2 c ells, but enhances the Spl-dependent activation of the promoter several fol d. Enhancement by AP-2 is observed only when Spl is limiting for transcript ion activation. These data suggest that the cellular AP-2/Sp1 ratio might i nfluence ANTE expression in developing or differentiating cells.