1cb6

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spinqualitylabelsall models 1cb6, resolution 2.0Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURE OF HUMAN APOLACTOFERRIN AT 2.0 A RESOLUTION.

Contents 1 Overview 2 Disease 3 About this Structure 4 Reference

Overview

The three-dimensional structure of a form of human apolactoferrin, in, which one lobe (the N-lobe) has an open conformation and the other lobe, (the C-lobe) is closed, has been refined at 2.0 A resolution. The, refinement, by restrained least-squares methods, used synchrotron, radiation X-ray diffraction data combined with a lower resolution, diffractometer data set. The final refined model (5346 protein atoms from, residues 1-691, two Cl- ions and 363 water molecules) gives a, crystallographic R factor of 0.201 (Rfree = 0. 286) for all 51305, reflections in the resolution range 10.0-2.0 A. The conformational change, in the N-lobe, which opens up the binding cleft, involves a 54 degrees, rotation of the N2 domain relative to the N1 domain. This also results in, a small reorientation of the two lobes relative to one another with a, further approximately 730 A2 of surface area being buried as the N2 domain, contacts the C-lobe and the inter-lobe helix. These new contacts also, involve the C-terminal helix and provide a mechanism through which the, conformational and iron-binding status of the N-lobe can be signalled to, the C-lobe. Surface-area calculations indicate a fine balance between open, and closed forms of lactoferrin, which both have essentially the same, solvent-accessible surface. Chloride ions are bound in the anion-binding, sites of both lobes, emphasizing the functional significance of these, sites. The closed configuration of the C-lobe, attributed in part to weak, stabilization by crystal packing interactions, has important implications, for lactoferrin dynamics. It shows that a stable closed structure, essentially identical to that of the iron-bound form, can be formed in the, absence of iron binding.

Disease

Known disease associated with this structure: Deafness, autosomal dominant 1 OMIM:[602121]

About this Structure

1CB6 is a Single protein structure of sequence from Homo sapiens with CL as ligand. Full crystallographic information is available from OCA.

Reference

Structure of human apolactoferrin at 2.0 A resolution. Refinement and analysis of ligand-induced conformational change., Jameson GB, Anderson BF, Norris GE, Thomas DH, Baker EN, Acta Crystallogr D Biol Crystallogr. 1998 Nov 1;54(Pt 6 Pt 2):1319-35. PMID:10089508

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