Figure 6.

mIIbN and mIIbN-mIIaCT are not internalized by PTH. OK cells were transfected with wt mIIa or mIIb cotransporters or with the mutants mIIbN and mIIbN-mIIaCT and processed for the PTH experiment (see Materials and Methods). Cells were incubated for 2 h with 10⁻⁸ M 1–34 PTH, and the patterns of green fluorescent cells before (Upper) and after (Lower) treatment were compared. Down-regulation of mIIa by 1–34 PTH is indicated by the disappearance of its specific “patches.” Results are representative of three independent experiments.