FIGURE 7.
Patch/FRAP studies demonstrate stable heteromeric interactions between TβRI and TβRII and distinguish between mutants based on the modulation of their interactions by TGF-β1. COS7 cells were co-transfected by myc-TβRI and an HA-tagged TβRII construct. Patching/labeling and patch/FRAP experiments were performed as in Fig. 5. Similar results (not shown) were obtained when the IgG/Fab′ labeling was swapped (IgG patching of myc and Fab′ labeling of the HA-tagged receptors). A, C, and E, average RF values. B, D, and F, average D values. Bars are mean ± S.E. of 30–40 measurements in each case. Asterisks indicate significant differences between the RF values of the pairs indicated by brackets (*, p < 0.05; **, p < 10-3; ***, p < 10-5).