Figure 3. Internalization of ¹²⁵I-ANP in HEK-293 cells expressing recombinant wild-type or mutant receptors.

HEK-293 cells expressing wild-type, G920A, D921A, Y923A or GDAY/AAAA mutant receptors were preincubated for 1 h at 4 °C with labelled ¹²⁵I-ANP. Surface ¹²⁵I-ANP binding to wild-type and mutant recombinant HEK-293 cells accounted for an average of approx. 28958±750 c.p.m. Cells were subsequently warmed at 37 °C for the indicated time periods to permit the internalization of ligand–receptor complexes into the cell interior. Internalization of ¹²⁵I-ANP was quantified at each time point as described in the Materials and methods section. The results represent the means±S.E.M. for triplicate experiments.