Fig. 7. The RXR motif is inactive when close to the membrane. (A) N-Terminal amino-acid sequence of Iip35 LI/ML and the mutants with deletions in this region. Positions 1 and 17 are the initiation sites of Iip35 and Iip33, respectively. The arginine residues in the RXR motif are underlined, the original position of the mutated leucine-based targeting signals are in black boxes, prolines in Iip33 region are in bold and the phosphorylated Ser8 is boxed. (B) The indicated invariant-chain molecules were transiently co-transfected in HEK 293T cells and tested after 48 hours. Cells were analysed by flow cytometry using BU45 either before (surface Ii) or after (total Ii) permeabilization with saponin. The ratios of surface to total Ii are shown.