(6S)-5-formyl-5,6,7,8-tetrahydrofolate(out) + 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole-4-carboxamide(in) = (6S)-5-formyl-5,6,7,8-tetrahydrofolate(in) + 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole-4-carboxamide(out) — reaction