1CB6

STRUCTURE OF HUMAN APOLACTOFERRIN AT 2.0 A RESOLUTION.

1CB6 の概要

• エントリーDOI: 10.2210/pdb1cb6/pdb
• 分子名称: Lactotransferrin, CHLORIDE ION (3 entities in total)
• 機能のキーワード: iron transport, apolactoferrin, conformational change
• 由来する生物種: Homo sapiens (Human)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 76334.17

構造登録者

Jameson, G.B.,Anderson, B.F.,Norris, G.E.,Thomas, D.H.,Baker, E.N. (登録日: 1999-03-01, 公開日: 1999-03-12, 最終更新日: 2024-11-20)

主引用文献

Jameson, G.B.,Anderson, B.F.,Norris, G.E.,Thomas, D.H.,Baker, E.N.
Structure of human apolactoferrin at 2.0 A resolution. Refinement and analysis of ligand-induced conformational change.
Acta Crystallogr.,Sect.D, 54:1319-1335, 1998

PubMed Abstract: 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.

PubMed: 10089508
DOI: 10.1107/S0907444998004417

実験手法

X-RAY DIFFRACTION (2 Å)