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Figure 7
Overview of the afamin structure models. Top left: the major binding site of afamin, corresponding to the Sudlow S1 drug-binding site in albumin, is located in the centre of the heart-shaped molecule between the equivalents of hSA domains I (HSA-I) and III (HSA-III). The entrance to the deep hydrophobic cleft harbours the Gd-DO3A chelate molecules, indicated by grey spheres. Top right: the four structure models of afamin [the monoclinic model MA (PDB entry 5okl chain A), the monoclinic model MB (PDB entry 5okl chain B), the dehydrated orthorhombic model OA (PDB entry 6fak chain A) and the orthorhombic form of the Gd-DO3A complex GD] are superimposed on hSA domain II (HSA-II). The motion of domains I and III towards each other affects access to the binding site. The first hexose molecules of the paucimannose basic glycosylations and the PEG molecules of the dehydrated model PDB entry 6fak chain A are also shown as ball-and-stick models. Bottom four panels: multi-conformer refinement trajectories of the four independent afamin models, illustrating the high degree of plasticity of the afamin molecule. The backbone trace is coloured from the N-terminus (blue) to the C-terminus (red). It is noticeable that in the four structure models from related crystal forms it is not always the same parts that are disordered and missing. Recognizable examples are the green connecting helix being well defined in MA but severely disordered in the high-resolution OA, while the N-terminal region (blue) is well ordered in OA but is disordered in MB. The higher overall disorder of GD and the absence of large parts of the C-terminus (red) in GD are also distinctive. Figures were produced with ICM-Pro from Molsoft (Abagyan et al., 2006BB1).

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ISSN: 2059-7983
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