Interaction between an intraluminal loop peptide of the inositol 1,4,5-trisphosphate receptor and the near N-terminal peptide of chromogranin A

Abstract

The near N-terminal region of chromogranin A (CGA) has been shown to be the secretory vesicle membrane binding region, and tetrameric chromogranin A has been demonstrated to bind four molecules of an intraluminal loop peptide of the inositol 1,4,5-trisphosphate (IP 3) receptor. It was therefore necessary to determine whether the conserved near N-terminal region of CGA interacts with the intraluminal loop region of the IP 3 receptor. In the present study, we found that the proposed anchor region of CGA, the conserved near N-terminal region, does indeed interact with the intraluminal loop region of the IP 3 receptor at the intravesicular pH of 5.5, further strengthening the case for the potential interaction between tetrameric chromogranins and tetrameric IP 3 receptors in the cell.