Figure 3.

Amplification of GRASP signal using antibodies recognizing reconstituted GFP. (A,B) Superfolder GFP is fluorescent when expressed in 293 cells (A) whereas split GFP1–10 is not (B). Chicken antibodies to bacterially expressed superfolder GFP recognize both proteins (A',B'). Blue channel shows counter-staining with Neurotrace 435. (C,D) Following absorption to sGFP1–10 and tissue, the same antibodies react with fluorescent superfolder GFP (C,C'), but not sGFP1–10 (D,D'). (E,F) Mouse monoclonal antibody Mab GFP-G1 recognizes both superfolder GFP (E) and split GFP1–10 (F). (G,G') Cells transfected with 1–10::NLG or 11::NXN were co-cultured and doubly stained with Mab GFP-G1 and chicken anti-rGFP. Mab GFP-G1 stained the sGFP1–10::NLG expressing cell. In contrast, anti-rGFP stains only contacts between sGFP1–10::NLG- and sGFP11::NXN-expressing cells (mab GFP-G1-positive and -negative, respectively). Bar, 20 μm for A–F; 5 μm for (G).