Tail-anchored (TA) proteins contain a single transmembrane domain (TMD) at the C-terminus. The post-translational insertion of TA proteins into the ER membrane requires the cooperation of the Golgi ER-trafficking (GET) complex, which contains Get1, Get2 and Get3. Get3 is a cytosolic ATPase which can recognize and bind the TMD of the TA proteins. Get1 and Get2 are ER transmembrane proteins which can recruit and form a complex with TA-bound Get3. The GET complex carries out an energy-dependent process that facilitates the insertion of the TA-protein TMD into the ER membrane. In order to investigate the mechanism by which the GET complex functions to promote protein insertion into the ER membrane, yeast Get3 has been crystallized. The crystals diffracted to 2.7 Å resolution using a synchrotron X-ray source. The crystals belonged to space group P21212, with unit-cell parameters a = 220.26, b = 112.95, c = 48.27 Å. There is one Get3 dimer in the asymmetric unit, which corresponds to a solvent content of approximately 65%. © 2009 International Union of Crystallography. All right reserved.