Abstract
Despite their importance in various cellular functions, the three-dimensional structure at atomic resolution has been determined for only a few membrane proteins. In his Perspective, Braun discusses results reported in the same issue by [ Ferguson et al .][1] in which the crystal structure of FhuA, an iron transporter protein, has been determined at high resolution. This and related proteins may be the general model for a large class of iron-transporting molecules. [1]: http://www.sciencemag.org/cgi/content/short/282/5397/2215