Relatively low correlated motion is observed between ATP and the most of the P, N, and A domains. There is relatively high correlation at the lumenal ends of the transmembrane helices, which may be important to regulate motion in order to prevent or allow ion flow. There is also a fairly conspicuous "pathway" of high correlation that extends down the back side of the SERCA pump (Fig. ), which may function to propagate the allosteric signal between the nucleotide binding site and the calcium binding site. There is relatively high correlation between the bound both nucleotides and Asp351, measured at 0.536 and 0.579 to ATP and dATP respectively. This makes the bound nucleotide (ATP or dATP) one of the most correlated residues to this autophosphorylation site. Surprisingly though, the bound Mg 2+ ion shows a stronger correlation to Asp351 than either nucleotide does to Asp351. Furthermore, there is an increase in correlation between Asp351 and Mg 2+ when transitioning from the apo state to either dATP or ATP bound. We see an increase in r M I from 0.523 to 0.600 and 0.637 for ATP and dATP respectively. This suggests that the binding of either nucleotide increases the strength of interaction to the Mg 2+ ion to the autophosphorylation site.