Figure 2.

Calmodulin binding to the FcRn cytoplasmic tail is specific, calcium-dependent, and reversible. (A) GST and the WT FcRn tail expressed as a GST fusion protein were incubated with CaM-Seph or Seph. GST and GST-tail proteins are shown as controls in lanes 1 and 2, respectively. Results are representative of four independent experiments. (B) WT and mutant GST-tail fusion proteins were incubated with CaM-Seph in the presence or absence of calcium. WT GST-tail protein is a control in lane 11. Results are representative of four independent experiments. (C) WT and mutant GST-tail fusion proteins were incubated with CaM-Seph in the presence or absence of calcium, and beads were washed with buffers containing calcium or EGTA. Fusion proteins are shown as controls in lanes 1–3. In each experiment, GST-fusion protein binding was assessed by immunoblot. Del, deletion mutant.