Abstract: Objective To investigate the ligand-binging characteristics of Veli3 PDZ. Methods Random peptide library was screened using yeast two-hybrid method with Veli3 PDZ as bait. In combination with bioinformatics method all the potential ligands in human proteome have been predicted by searching human databases with the consensus-binding sequences. Fourteen native human proteins predicted as ligands were chosen by their cellular locations and biological functions for validating protein interaction in yeast two-hybrid system. Results The C-terminal consensus sequences for the Veil3 PDZ binding is [E/X][S/T]X[V/I/L]-COOH (X denotes any amino acid), which indicates that Veli3 PDZ belongs to classⅠ. Six of fourteen native human proteins predicted as ligands were confirmed positive in the yeast two-hybrid system. There are a lot of interactions between PSD-95, another PDZ protein, and the ligands of Veli3 PDZ reported previously and discovered in this study. Conclusion The six novel potential ligands of Veli3 found in this study provide significant clues for discovering biological functions of Veil3 proteins. Moreover, Veli3 PDZ and PSD-95 PDZ may compete with each other to bind the same ligands.

Key words: protein interaction, PDZ domain, yeast two hybrid, bioinformatics