Figure 6.

Calmodulin binds Cyk1p in the presence of calcium. Cmd1-GST or GST control beads were incubated with extract plus or minus 5 mM CaCl₂ as described in MATERIALS AND METHODS. Samples were analyzed by immunoblot analysis. (A) Cmd1-GST binds full-length Cyk1p in the presence of calcium. ext, RLY230 extract. All lanes were immunoblotted with mouse anti-myc antibody. (B) The IQ motifs of Cyk1p are not required for Cmd1p binding. ext, RLY556 extract. Samples were immunoblotted with mouse anti-myc antibody. (C) IQ motifs of Cyk1p are not sufficient for Cmd1p binding. ext, RLY578. Samples were immunoblotted with mouse anti-HA antibody. (D) A schematic diagram summarizing the results from the GST-Cmd1 pull-down experiments using extracts expressing various Cyk1 deletions. Cmd1-GST was able to bind Cyk1ΔIQp, Cyk1ΔGRDp, and Cyk1ΔCHDp in the presence (but not absence) of calcium. Cmd1p was unable to bind either Cyk1ΔN or IQ motifs overexpressed in yeast extracts.