S-glutathionylation of human transporter ABCB10 does not directly regulate ATPase activity.

The mitochondrial ATP-Binding cassette transporter ABCB10 is essential for healthy heme biosynthesis and protection/recovery from oxidative stress. Previously, mouse ABCB10 was proposed as a target for regulation by S-glutathionylation in response to redox changes. Here, we studied purified human ABCB10 in vitro to determine the transporter's potential modification by glutathione and any direct effect on ATPase activity. Western blotting following incubation with reduced and oxidized glutathione confirmed human ABCB10 is targeted for S-glutathionylation under oxidative conditions. Selective mutagenesis analysis identified C582 as the site for this reversible modification. However, we found no relevant effect on the transporter's ATPase activity in response to S-glutathionylation. Altogether, our findings suggest S-glutathionylation does not directly regulate the activity of purified ABCB10 at physiological temperature.