FIG 6.

Liganded erbB3 receptor pairs show correlated motion and reduced diffusion at small separation distances. Uncorrelated jump distance and jump magnitude of QD pairs on SKBR3 cells are plotted as a function of separation distance. Correlated motion is indicated by a reduction in uncorrelated jump distance (blue) at small separation distances. A similar reduction in jump magnitude (red) indicates reduced diffusion of interacting receptors. Error bars represent standard error of the mean. (A) Ligand-bound endogenous erbB3 pairs in SKBR3 cells show correlated motion. (B) Preincubation with 100 nM lapatinib reduces correlated motion of ligand bound erbB3 receptors, as shown by larger displacement at short separation distances. (C) In SKBR3 cells expressing HA-erbB3, unliganded HA-erbB3 receptors show no correlated motion. (D) The addition of 12 nM unlabeled HRG results in correlated motion at small separation distances. (E) Pairs of ligand-bound receptors (HA-erbB3 or endogenous erbB3) tracked with QD-HRG probes in SKBR3 HA-erbB3 cells show correlated motion similar to endogenous erbB3 in SKBR3 cells (see panel A).