Ion pumps made crystal clear

摘要

The function of every cell in our bodies depends on the work of proteins known as ion pumps. Several new crystal structures cast fresh light on how three different pumps deal with their distinct cargoes of ions. Ion pumps toil tirelessly in cells throughout all kingdoms of life, transporting ions across membranes. To investigate the workings of these microscopic machines, X-ray crystal structures of a calcium ion pump known as SERCA have been determined. But although those structures depict SERCA in several conformations, none of them caught the pump in the act of releasing its cargo of ions. Moreover, nagging questions remained about how much SERCA might differ from other, genetically related ion pumps — such as those that transport ions of different sizes and charges from calcium, or that require additional protein subunits. In this issue, three papers from the same group go a long way towards addressing those concerns by describing the first atomic structures of a SERCA pump with its ion pathway open and of two related proteins — a sodium-potassium pump and a proton pump.