Gustatory receptor which mediates acceptance or avoidance behavior, depending on its substrates. Seems to be involved in the sensing of bitter taste since it is expressed in neurons that mediate sensitivity to bitter compounds which are also avoidance-type taste neurons. Taste bristles on the labial palp, labral and cibarial sense organs, chemosensory bristles on the leg and anterior wing margin. In larvae, is expressed in neurons of the terminal external chemosensory organ and in the dorsal pharyngeal sense organ. Neurons expressing Gr22e also express Gr66a and correspond to taste neurons that mediate sensitivity to bitter compounds. Belongs to the insect chemoreceptor superfamily. Gustatory receptor (GR) family. Gr22e subfamily.