The C-terminal part of VIP is important for receptor binding and activation, as evidenced by chimeric constructs of VIP/secretin

The structural requirements of vasoactive intestinal polypeptide (VIP) for receptor binding and cAMP production were studied in a cell line stable transfected with the cDNA for rat VIP receptor 1 (rVIPR 1). Using a number of chimeric constructs of VIP and the homologue peptide secretin, it was found that the N-terminal half of VIP (1-11) can be exchanged with the corresponding sequences in secretin with only modest influence on binding and activation, whereas the opposite chimeras with N-terminal VIP and C-terminal secretin were unable to bind to the VIP receptor. The data suggest that the C-terminal region of VIP is important for receptor binding and activation.