FIG. 5.

The intact PDX-1 homeodomain interacts physically with E47/Pan1. (A) In vitro-translated, ³⁵S-labeled PDX-1 (wild type and deletion mutants) was incubated with GST-E47/Pan1 fusion protein immobilized on glutathione-Sepharose beads, and bound proteins were resolved by SDS-PAGE followed by autoradiography. GST alone was used as a control. (B) Ten percent of the ³⁵S-labeled PDX-1 (wild-type and deletion mutant) proteins used in the binding assay were resolved by SDS-PAGE. (C) In vitro-translated, ³⁵S-labeled E47/Pan1 protein was incubated with GST alone or with GST fused to the truncated PDX-1 proteins shown. Bound proteins were immobilized on glutathione-Sepharose beads and resolved by SDS-PAGE followed by autoradiography. Ten percent of the ³⁵S-labeled E47/Pan1 protein used in the binding assay was loaded in lane 1. (D) Structures of the PDX-1 deletion mutants and summary of the results. AD, transcription activation domain; HD, homeodomain; A to E, conserved segments of the PDX-1 activation domain as described by Peshavaria et al. (40).