FIG. 5.
The CSF-1 receptor transmembrane domain directs degradation of the insulin receptor cytoplasmic domain. 293 cells were transfected with expression constructs for the wild-type insulin receptor (IR; lanes 1 to 3), the CSF-1R/IRtm-cyto chimera (lanes 4 to 6), the CSF-1R/IRcyto chimera (lanes 7 to 9), or a control plasmid (lane 10). Cells were left untreated (lanes 1, 4, and 7) or were stimulated with PMA for 15 min (lanes 2, 5, 8, and 10) or for 1.5 h (lanes 3, 6, and 9). The cells were lysed and analyzed by immunoprecipitation and immunoblotting with an antiserum against the insulin receptor β chain.