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, sulfate and thiosulfate, and, to a lesser extent, other nucleotides (PubMed:26140942, PubMed:26444389). Binds calcium ions Ca(2+) (PubMed:22062157). Mediates also calcium uptake (PubMed:26444389). Counter-exchange transport activity is saturable and inhibited by pyridoxal-5'-phosphate, EDTA and EGTA (PubMed:26140942, PubMed:26444389). 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, PubMed:26444389). 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 in flowers, leaves, stems, roots and seedlings, mostly in aerial parts. Slightly expressed in flower petals. The N-terminal domain can bind calcium. Belongs to the mitochondrial carrier (TC 2.A.29) family. Extended N-terminus.