Kinetic parameters of membrane preparations of HEK293 stably overexpressing pGC-A for various nucleotides.

NC activities were analyzed as mentioned in Materials and Methods. Membranes from HEK293 cells overexpressing pGC-A (10–80 µg of protein per tube) were incubated with 2–7,500 µM (XTP/Me2+: 2–2,000 µM) NTP/Me2+ in the presence of 1 µM ANP at 37°C for 5–10 min depending on the analyzed NTP. Apparent s0.5, Vmax, and nHill represent the means ± SEM of six independent experiments shown in Figs. 1 and 2 and are given in alphabetical order of NTPs. Curves were analyzed by nonlinear regression using Prism version 5.0. nd: not detected, nq: not quantified.
*only detectable in the presence of 500 µM ATP/Mg2+.