Structural biology of ion pumps (P-type ATPases)

Ion pump proteins are membrane proteins that are integrated into biological membranes (lipid bilayers). They are powered by ATP and are enzymes that hydrolyse ATP (ATPase). We have been working on crystal structure determination and molecular dynamics simulations of Ca2+-ATPase from skeletal muscle sarcoplasmic reticulum (SERCA1a). At present crystal structures are determined for 9 intermediates that approximately cover the entire reaction cycle. Thus, we can say that the mechanism of ion pumping is roughly understood and answer fundamental questions, for instance, what ATP and phosphorylation do, why nearly 100% efficiency of energy conversion is possible, why the structure of ion pump has to be so. The focus of this article is on the gating mechanism of ion pathway. (author)