The divalent zinc cation is found in multiple guises in prokaryotic and eukaryotic cells. Lu and Fu (see the Perspective by Nies) present the 3.8 angstrom structure of YiiP, a bacterial membrane protein that imports Zn2+ by exchanging it for H+. The structure of YiiP is a Y-shaped homodimer, through which a presumptive pathway for Zn2+/H+ exchange can be discerned. YiiP is a member of the cation diffusion facilitator family of transport proteins. Another family member, ZnT-8, is expressed solely in pancreatic β cells and has recently been associated with risk for type 2 diabetes.