And these calcium ions do two different things. Number one, the calcium ions find a ubiquitous protein molecule we call calmodulant. And we'll discuss the specifics of what calmodulen does and what it looks like in a future lecture. But basically the calmodulen looks like this. It looks like a hand and it has a side, a pocket that binds that calcium. And once it binds the calcium, it forms the calcium calmodulent complex.