Cell membrane; Multi-pass membrane protein . Apical cell membrane; Multi-pass membrane protein . Basolateral cell membrane; Multi-pass membrane protein .
Tissue Expression
Placenta, liver, and to a much smaller extent, in lung.
Signaling_pathway
Research Areas
Function
Transporter that mediates the import of reduced folates and a subset of cyclic dinucleotides . Has high affinity for N5-methyltetrahydrofolate, the predominant circulating form of folate . Also able to mediate the import of antifolate drug methotrexate . Acts as an importer of immunoreactive cyclic dinucleotides, such as cyclic GMP-AMP (2'-3'-cGAMP), an immune messenger produced in response to DNA virus in the cytosol, and its linkage isomer 3'-3'-cGAMP . Mechanistically, acts as an antiporter, which export of intracellular organic anions to facilitate uptake of its substrates . 5-amino-4-imidazolecarboxamide riboside (AICAR), when phosphorylated to AICAR monophosphate, can serve as an organic anion for antiporter activity .