Figure 1.

Cell adhesion activity of transfectants which express mutant neuropilin-1 proteins (Part 1). (A) A schematic representation of mutant neuropilin-1s. NP-full, intact neuropilin-1; NP-bc, neuropilin-1 lacking the a1 and a2 domains; NP-c, neuropilin-1 protein lacking the a1, a2, b1, and b2 domains; NP-abcp, neuropilin-1 whose transmembrane and cytoplasmic regions are replaced by that of the Xenopus plexin. (B) Immunoblot of transfectants expressing intact and mutant neuropilin-1 proteins, by using an antibody raised against the b1-c domains. The number followed by the name of the construct represents the clone number. (C) Quantification of cell aggregation activity of the mutant neuropilin-1s. The degree of aggregation of transfectants is expressed by the index N_t/N₀, where N_t and N₀ are the total particle number at incubation times t and 0, respectively. White and black bars represent N₃₀/N₀ and N₆₀/N₀, respectively. (D–F) Cell aggregation at 60 min in gyration, detected by phase contrast (D and E) or fluorescence microscope (F). Parental L cells do not show cell aggregability (D). In contrast, fluorescein-labeled parental L cells and transfectants expressing NP-full 86 form mixed cell aggregates (E and F). E and F show the same field. Bar, 100 μm.