Figure 4.

Kinetics of heme insertion into FlAsH-TC-sGCβ1(1–619) WT, heme binding–deficient mutants, and HSP90-binding mutant proteins in mammalian cells. TC-sGCβ1(1–619) WT and mutants were expressed in heme-deficient COS-7 cells. The proteins were FlAsH-labeled, and then their fluorescence was monitored with time after adding 5 μm heme to the cell cultures. The fluorescence decrease is proportional to the heme insertion into the TC-sGCβ1(1–619) proteins over time. In some cases, the initial rates of fluorescence decrease were estimated by fitting (red lines). Curve points show the mean ± S.D. (error bars) from three wells and are representative of three independent experiments.