Fig. 6. The intracellular domain of teneurin-2 is released from the cell membrane. (A) Detection of nuclear activity of transmembrane BDAD-teneurin-2 fusion proteins by induction of a luciferase reporter gene. HT1080 cells transfected with various BDAD-teneurin-2 fusion constructs and a construct expressing only BD (negative control) were analysed for luciferase activity of the co-transfected luciferase reporter plasmid. (B) Luciferase activity obtained by transfection of BDAD-ITEY (left bars) or BDAD-IT (right bars) into HT1080 control cells (bars a, HT-control) or cells stably expressing TEY (bars b, TEY cells). The ratio of the values obtained for each construct in TEY cells versus the values obtained in HT-control cells is given above the bars. (C) A model is proposed for the activation of the release of the intracellular domain by homophilic interaction between the C-terminal parts of the teneurin-2 extracellular domains on the basis of the data presented in this figure and in Table 1, showing a 6.5-fold induction of luciferase activity of BDAD-ITEY/BDAD-IT in TEY cells, whereas no difference is obtained when the same experiments are performed in TE cells (data of Table 1).