Depending upon how the precursor peptide, or pro-protein, is cleaved and processed you may find that yest cannot process the ligand appropriately. Thus, I think it would be best to express the mature peptide ligand rather than the pro-protein.

Thanks for your suggestion. I agree with your point however, the mature ligand peptide is just 23 amino acid sequence so, possibly It would be doable to clone this short fragment into the bait vector but it may not be sufficient enough to be transformed into yeast.. Also, the cleavage process from the pro-peptide is still unknown just that its been shown the peptide is cleaved from the carboxy terminus of the precursor protein.

So now I am not sure to clone the mature ligand or the pro-peptide?