Mature neuropeptides are processed from precursor proteins, which often contain many related peptide sequences that are flanked by processing sites. The processing sites consist of basic or di-basic amino acids, which are recognized and cleaved by specific proteases. No neuropeptide precursor protein structure has been solved.
Efforts are currently underway to overexpress the protein.
The Ascaris and C. elegans proteins have very little amino acid sequence similarity but have several common characteristics, such as length of proteins and placement of peptides. By solving the structures of these, and other related proteins, we will gain insight into the role of structure in the regulation of neuropeptide expression as well as into the evolution of these important signaling molecules.