FIGURE 4.

PTH stabilizes the high molecular mass form of the PTHR. A–C, CHO cells stably expressing HA-PTHR were pulse-labeled with [³⁵S]methionine/cysteine-containing medium (150 μCi/ml) and then chased for the indicated times with medium containing nonradioactive methionine and cysteine in the absence (A) or presence of 100 nm PTH(1–34) (B) or 1 μm PTH(7–34) (C). HA-PTHR was precipitated from cell lysates using HA antibody. The samples were analyzed by SDS-PAGE and fluorography of the dried gels with a Bio-Rad phosphorimager. The closed arrowheads indicate newly synthesized PTHR; the open arrowheads indicate fully mature PTHR. D, decay of radiolabeled PTHR was quantified using a monoexponential decay function. ▴, untreated; ○, PTH(1–34); ●, PTH(7–34). The means of three independent experiments are shown.