Calcium-dependent mitochondrial carrier protein that catalyzes the import of ATP co-transported with metal divalent cations across the mitochondrial inner membrane in exchange for phosphate (Pi) (PubMed:22062157, PubMed:28695448, PubMed:26140942, PubMed:26444389). Can transport phosphate, AMP, ADP, ATP, adenosine 5'-phosphosulfate and, to a lesser extent, other nucleotides (PubMed:26140942, PubMed:26444389). Binds calcium ions Ca(2+) (PubMed:22062157). Mediates also calcium uptake (By similarity). Counter-exchange transport activity is saturable and inhibited by pyridoxal-5'-phosphate, EDTA and EGTA (PubMed:26140942). Activated by calcium Ca(2+) and manganese Mn(2+) ions, and slightly by iron Fe(2+) and zinc Zn(2+) ions (PubMed:26140942, PubMed:28695448). Repressed by copper ions Cu(2+) and slightly by magnesium Mg(2+) ions (PubMed:28695448). Magnesium Mg(2+) ions promotes slightly ATP uptake, ATP-Mg(2+) being exchanged with ATP(4-) (PubMed:26444389). Expressed at high levels in flowers, leaves, stems, roots and seedlings, mostly in flowers. Slightly expressed in vascular tissues, in leaves of both seedlings and mature plants, stamen filaments and developing siliques. By stress conditions. The N-terminal domain can bind calcium. Belongs to the mitochondrial carrier (TC 2.A.29) family.