Fig. 5. An intact AP-2 binding domain in arrestin is necessary for norpA-induced endocytosis of persistent rhodopsin-arrestin complexes. Cross sections (0.75 µm) from a frozen Drosophila retina were stained with both arrestin and rhodopsin antibodies followed by fluorescein and rhodamine-labeled secondary antibodies, respectively. (A-C) norpA, (D-F) norpA; arr2^K391A and (G-I) norpA; arr2^R393A. The flies were dark-reared and then treated with constant room light for 24 hours prior to fixation. Dissected eyes were fixed and sectioned as described in Materials and Methods. A, D and G were stained with arrestin-specific antibodies, B, E and H were stained with rhodopsin-specific antibodies, C, F, and I are merged images.