Role of the nicotinic acid group in NAADP receptor selectivity

We then investigated both their affinity for the NAADP binding site in sea urchin egg homogenates and their ability to activate the NAADP sensitive Ca2+ channel. We hereby show that a negative charge at the 3′ position is an important determinant of affinity but the protein displays a large tolerance for the size of the group. Furthermore, the protein does not easily accommodate multiple charged groups or large uncharged groups.