Fig. 4. LAMP binds with highest affinity to OBCAM and CEPU-1. CHO cell lines were grown in 96-well plates and incubated with varying concentrations of chimaeric proteins. (A) For LAMP-CHO, strong binding was observed with OBCAM-Fc and CEPU-1-Fc, both of which displayed almost identical absorbance for each concentration tested. However, with LAMP-Fc, the absorbance remained at background levels, even at 10 µg ml^–1. (B) For OBCAM-CHO, highest absorbance values were observed with LAMP-Fc at 10 µg ml^–1 (0.75), as predicted by the previous result. The next highest was CEPU-1-Fc at 10 µg ml^–1 (0.35) and the lowest was OBCAM-Fc at 10 µg ml^–1 (0.2). (C) For CEPU-CHO, highest absorbance was observed with LAMP-Fc at 10 µg ml^–1 (0.8), followed by CEPU-1-Fc at 10 µg ml^–1 (0.7) and the lowest was OBCAM-Fc at 10 µg ml^–1 (0.35), as expected. Error bars lie within the symbol for some points. (D) Taking together the relative affinities of the homophilic interactions from Fig. 3 and the comparative affinity of the homo- and heterophilic interactions, we propose this hierarchy for the relative affinity of IgLON interactions in trans.