FIGURE 5.

The ¹²⁵I-labeled G₃ peptide from protein 4.2 binds to the α-spectrin EF-domain and a minispectrin heterodimer. Increasing concentrations of the ¹²⁵I-labeled G₃ peptide from protein 4.2 were incubated with various GST-tagged spectrin peptides, and bound ¹²⁵I-labeled G₃ peptide was measured after retrieval of the GST peptides on GSH-Sepharose beads. A, GST-αEF and GST-αEFΔ13 (0.60 μm each) are shown. B, GST-α18–21EF and GST-α18–21EFΔ13 (0.20 μm each) are shown. C, GST-minispectrin with or without the αEFΔ13 mutation (0.34 μm each) is shown.