Identification of the secretory vesicle membrane binding region of chromogranin A1

In the past a synthetic peptide representing the conserved near N-terminal region of chromogranin B (CGB) (residues 17-36) has been shown to interact with the vesicle membrane. Hence, it was necessary to confirm this observation with CGB deletion proteins. In order to address this need and to confirm the published sequence of CGB, we cloned a CGB gene and produced various CGB deletion proteins. The recombinant CGB protein lacking the first 15 (rCGB 16-626) or 16 amino acid residues (rCGB 17-626) bound to the vesicle membrane as well as the full-length CGB. However, rCGB 49-626, lacking the conserved near N-terminal region, failed to interact with the vesicle membrane, indicating an anchor role for the conserved near the N-terminal region.