Fig. 4.

Trans DSCAM interactions mask the CDH3 adhesive response. Cortical neurons from wild-type (A and D) and Dscam^−/− (B and E) mice were transfected with constructs encoding CDH3 with a C-terminal FLAG tag (green) and then incubated for 1 h with beads coated with CDH3 and DSCAM ectodomains (A and B, magenta) or CDH3-EC alone (D and E, magenta). The accumulation of CDH3-FLAG at sites of contact between beads and neurons was quantified (C and F). In all four conditions, CDH3 was present both in the neuron and on the bead. While neuronal CDH3-FLAG was largely indifferent to the beads when DSCAM was both in the neuron and on the bead (A), CDH3 accumulated at these sites when DSCAM was present only on the bead (B), only in the neuron (D), or completely absent (E), demonstrating that trans DSCAM interactions masked this accumulation. Means ± SEM are presented in C and F. n = 20 to 31 neurons per condition, from cultures separately prepared from three different mice per genotype (actual n values are noted in C and F). ***P < 0.001 by two-tailed Student’s t test. (Scale bar: 10 μm.)