Probable ATPase of unknown function. Its presence in a non-photosynthetic plant (Epifagus virginiana) and experiments in tobacco indicate that it has an essential function which is probably not related to photosynthesis. The nonsense codons at positions 344, 744, 861, 1131, 1255, 1805, 2158 and 2307 are modified to sense codons. Belongs to the Ycf2 family.