Figure 7.

PTH regulation of mutated NaPi cotransporters. OK cells were transfected with wt mIIa or mIIb cotransporters or with the mutants mIIbKR, mIIaNI, mIIaT505A, and mIIbS522A 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) the treatment were compared. Down-regulation of mIIa and mIIbKR by 1–34 PTH is indicated by the disappearance of their specific “patches.” Results are representative of 4 to10 independent experiments.