1cb6
From Proteopedia
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'''STRUCTURE OF HUMAN APOLACTOFERRIN AT 2.0 A RESOLUTION.''' | '''STRUCTURE OF HUMAN APOLACTOFERRIN AT 2.0 A RESOLUTION.''' | ||
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[[Category: Norris, G E.]] | [[Category: Norris, G E.]] | ||
[[Category: Thomas, D H.]] | [[Category: Thomas, D H.]] | ||
| - | [[Category: | + | [[Category: Apolactoferrin]] |
| - | [[Category: | + | [[Category: Conformational change]] |
| - | [[Category: | + | [[Category: Iron transport]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:32:39 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 09:32, 2 May 2008
STRUCTURE OF HUMAN APOLACTOFERRIN AT 2.0 A RESOLUTION.
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.
About this Structure
1CB6 is a Single protein structure of sequence from Homo sapiens. 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 Page seeded by OCA on Fri May 2 12:32:39 2008
