DRAP. N2a cells were transfected with either α4-GFP and α4-mCherry (A1, A2, B1, and B2 show exemplar data) or β2-GFP and β2-mCherry (C1, C2, D1, and D2 show exemplar data). The acceptor fluorophore (mCherry) was photobleached, causing an increase in fluorescence of the donor fluorophore (GFP). α4-GFP and α4-mCherry were co-transfected either with empty vector (A1, A2) or with lynx1 (B1, B2). β2-GFP and β2-mCherry were co-transfected either with empty vector (C1 and C2), or with lynx1 (D1 and D2). Lynx1 increases FRET efficiency between α4 subunits, but not between β2 subunits. E, lynx1 increases FRET efficiency between α4-GFP and α4-mCherry subunits when no other subunits are present (top left) and also when co-transfected with β2 (bottom left). lynx1 does not increase FRET efficiency between fluorescently tagged β2 subunits either without α4 present (top right) or with co-transfected α4 (bottom right). F and G, lynx1 has no effect on the ratio of signals, GFP/mCherry for fluorescently tagged α4 (F) or β2 (G). The numbers within parentheses in the bars represent number of cells per condition.