Crystals were obtained by vapor diffusion after 18 months from a 60-mg/ml solution of His-tagged Nab2 (residues 1–105) with a well buffer containing 0.2 M MgCl2, 0.1 M Tris–HCl, pH 8.5, and 20% (w/v) polyethylene glycol 4000. Crystals were cryoprotected in well buffer containing 20% glycerol and vitrified in a stream of anhydrous nitrogen at 100 K. A 1.8-Å-resolution data set (Table 3) was collected at 100 K in-house using a Rigaku X-ray generator equipped with Osmic mirrors and a MARdtb image plate detector. Data were processed using MOSFLM45 and reduced using SCALA and TRUNCATE.48 A molecular replacement was obtained using Phaser48 using the average NMR structure for residues 6–82 as a structural model. After solvent flattening using DM,48 the best molecular replacement solution was used as a starting model in ArpWarp48 that successfully built residues 6–94. After iterative cycles of refinement with REFMAC5 and model building using O49 and the addition of 59 water molecules, a final structure with an R-factor of 20.7% (Rfree = 26.4%) and excellent geometry was produced (Table 2). Modeling TLS rigid-body motion based on helices H1–H4 and helix H5 reduced the R-factor to 19.2% (Rfree = 25.0%).