And in fact, a single calcium or a single calmodulen can actually take up four calcium ions. And so these calmodulent proteins can actually be used by the cell to detect increase in calcium ion concentration. So if the calcium ion concentration increases to about five times of what it should be during steady state conditions, so from 100, about 500 nm, these calmodulent proteins can begin to bind those calcium ions. Now, once they bind the calcium ions, what happens next? Well, as soon as that calcium binds onto the calmodulant, as we saw in this particular discussion, it creates a conformational change in that calmodulent. And what that does is exposes crucial hydrophobic regions that weren't exposed before.