FIGURE 4.

Distinct cytoplasmic motifs in Sdc1 and Sdc4 engage the β4 cytoplasmic domain. The glutathione bead pulldown assay is used to assess the capture of His₆-β4(1677–1752) (prey) either by S1CD or S4CD (bait) in the presence of competing peptides. Captured β4 construct is visualized on Western blots by staining with anti-penta-His. A, capture by GST-S1CD or GST-S4CD in the presence of 0–300 μm KQEEFYA peptide sequence derived from the Sdc1 or PTNEFYA derived from Sdc4. The conserved C2 region (EFYA) is shown in bold. B, capture by GST-S1CD in the presence of Sdc1-specific peptide in which Phe-308 is mutated to Ala (A), or Tyr-309 is phosphorylated (Z), or is mutated to Ala or Phe (F). C, capture by GST-S1CD in the presence of Sdc1-specific peptide in which individual amino acids are mutated to Ala or Ala-310 is deleted.