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| | {{STRUCTURE_2gw5| PDB=2gw5 | SCENE= }} | | {{STRUCTURE_2gw5| PDB=2gw5 | SCENE= }} |
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| - | '''Crystal Structure of LIR-2 (ILT4) at 1.8 : differences from LIR-1 (ILT2) in regions implicated in the binding of the Cytomegalovirus class I MHC homolog UL18'''
| + | ===Crystal Structure of LIR-2 (ILT4) at 1.8 : differences from LIR-1 (ILT2) in regions implicated in the binding of the Cytomegalovirus class I MHC homolog UL18=== |
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| - | ==Overview==
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| - | BACKGROUND: Leukocyte Immunoglobulin-like Receptor-1 (LIR-1) and LIR-2 (also known as ILT2 and ILT4 respectively) are highly related cell surface receptors that bind a broad range of class I MHC molecules with low (microM) affinities. Expressed on monocytic cells and macrophages, both molecules transmit inhibitory signals after binding ligands. In addition to binding host class I MHC, the LIR-1 molecule, which is also expressed on lymphoid tissues, binds with a high (nM) affinity to UL18, a class I MHC homolog encoded by Human Cytomegalovirus (HCMV). In comparison, LIR-2 binds UL18 only weakly (microM KD). To understand how HCMV preferentially targets the more broadly expressed LIR-1 molecule, we determined the crystal structure of a ligand-binding fragment of LIR-2, and compared this to the existing high-resolution crystal structure of LIR-1. RESULTS: Recombinant LIR-2 (domains 1 and 2) was produced in E. coli and crystallized using streak seeding to optimize the crystal morphology. A data set complete to 1.8 A was collected at 100 K from a single crystal in the P4(1)2(1)2 spacegroup. The structure was solved by molecular replacement, using a search model based on the LIR-1 structure. CONCLUSIONS: The overall structure of LIR-2 D1D2 resembles both LIR-1, and Killer Inhibitory Receptors, in that the A strand in each domain forms hydrogen bonds to both beta sheets, and there is a sharp angle between the two immunoglobulin-like domains. However, differences from LIR-1 are observed in each domain, with two key changes apparent in the ligand-binding domain, D1. The region corresponding to the residue 44-57 helix of LIR-1 adopts a topology distinct from that of both LIR-1 and the KIR structures, involving a shortened 310 helix. Secondly, the predicted UL18 binding region of LIR-1 is altered substantially in LIR-2: the 76-84 loop mainchain is displaced 11 A with respect to LIR-1, and Tyrosine 38 adopts an alternative rotamer conformation. In summary, the structure of LIR-2 has revealed significant differences to LIR-1, including ones that may help to explain the >1000-fold lower affinity of LIR-2 for UL18.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_12390682}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12390682 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12390682}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Willcox, B E.]] | | [[Category: Willcox, B E.]] |
| | [[Category: Ig like domain]] | | [[Category: Ig like domain]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 05:36:38 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 12:38:49 2008'' |
Revision as of 09:38, 28 July 2008
Template:STRUCTURE 2gw5
Crystal Structure of LIR-2 (ILT4) at 1.8 : differences from LIR-1 (ILT2) in regions implicated in the binding of the Cytomegalovirus class I MHC homolog UL18
Template:ABSTRACT PUBMED 12390682
About this Structure
2GW5 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structure of LIR-2 (ILT4) at 1.8 A: differences from LIR-1 (ILT2) in regions implicated in the binding of the Human Cytomegalovirus class I MHC homolog UL18., Willcox BE, Thomas LM, Chapman TL, Heikema AP, West AP Jr, Bjorkman PJ, BMC Struct Biol. 2002 Oct 11;2:6. PMID:12390682
Page seeded by OCA on Mon Jul 28 12:38:49 2008
