1bqs
From Proteopedia
(New page: 200px<br /> <applet load="1bqs" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bqs, resolution 2.2Å" /> '''THE CRYSTAL STRUCTUR...) |
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caption="1bqs, resolution 2.2Å" /> | caption="1bqs, resolution 2.2Å" /> | ||
'''THE CRYSTAL STRUCTURE OF MUCOSAL ADDRESSIN CELL ADHESION MOLECULE-1 (MADCAM-1)'''<br /> | '''THE CRYSTAL STRUCTURE OF MUCOSAL ADDRESSIN CELL ADHESION MOLECULE-1 (MADCAM-1)'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is a | + | BACKGROUND: Mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is a cell adhesion molecule that is expressed on the endothelium in mucosa, and guides the specific homing of lymphocytes into mucosal tissues. MAdCAM-1 belongs to a subclass of the immunoglobulin superfamily (IgSF), the members of which are ligands for integrins. Human MAdCAM-1 has a unique dual function compared to other members in the same subclass in that it binds both the integrin alpha4beta7, through its two IgSF domains, and a selectin expressed on leukocytes, via carbohydrate sidechains. The structure determination of the two IgSF domains and comparison to the N-terminal two-domain structures of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecules (ICAM-1 and ICAM-2) allow us to assess the molecular basis of the interactions between integrins and their preferred ligands. RESULTS: The crystal structure of a fragment containing the two IgSF domains of human MAdCAM-1 has been determined to 2.2 A resolution. The structure of MAdCAM-1 reveals two separate integrin-recognition motifs. The key integrin-binding residue, Asp42, resides in the CD loop of domain 1; a buried arginine residue (Arg70) plays a critical role in maintaining the conformation of this loop. The second binding site is associated with an unusual long D strand in domain 2. The D and E strands extend beyond the main body of the domain, forming a negatively charged beta ribbon unique to MAdCAM-1. This ribbon is located on the same face as the key aspartate residue in domain 1, consistent with evidence that it is involved in integrin binding. CONCLUSIONS: The structural comparison of MAdCAM-1 to other members of the same IgSF subclass reveals some interesting features. Firstly, MAdCAM-1, like VCAM-1, has the key integrin-binding residue located on the protruding CD loop of domain 1 and binds to an integrin that lacks an I domain. This is in contrast to ICAM-1 and ICAM-2 where the key residue is located at the end of the C strand on a flat surface and which bind to integrins that contain I domains. Secondly, architectural differences in the CD loops of MAdCAM-1 and VCAM-1 cause an 8 A shift in position of the critical aspartate residue, and may partly determine their binding preference for different integrins. Finally, the unusual charge distribution of the two-domain fragment of MAdCAM-1 is predicted to orient the molecule optimally for integrin binding on the top of its long mucin-like stalk. |
==About this Structure== | ==About this Structure== | ||
| - | 1BQS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with NDG as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1BQS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=NDG:'>NDG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BQS OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Briskin, M | + | [[Category: Briskin, M J.]] |
| - | [[Category: Casasnovas, J | + | [[Category: Casasnovas, J M.]] |
| - | [[Category: Liu, J | + | [[Category: Liu, J H.]] |
| - | [[Category: Springer, T | + | [[Category: Springer, T A.]] |
[[Category: Tan, K.]] | [[Category: Tan, K.]] | ||
| - | [[Category: Wang, J | + | [[Category: Wang, J H.]] |
[[Category: NDG]] | [[Category: NDG]] | ||
[[Category: cell adhesion glycoprotein]] | [[Category: cell adhesion glycoprotein]] | ||
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[[Category: madcam-1]] | [[Category: madcam-1]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:58:06 2008'' |
Revision as of 09:58, 21 February 2008
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THE CRYSTAL STRUCTURE OF MUCOSAL ADDRESSIN CELL ADHESION MOLECULE-1 (MADCAM-1)
Overview
BACKGROUND: Mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is a cell adhesion molecule that is expressed on the endothelium in mucosa, and guides the specific homing of lymphocytes into mucosal tissues. MAdCAM-1 belongs to a subclass of the immunoglobulin superfamily (IgSF), the members of which are ligands for integrins. Human MAdCAM-1 has a unique dual function compared to other members in the same subclass in that it binds both the integrin alpha4beta7, through its two IgSF domains, and a selectin expressed on leukocytes, via carbohydrate sidechains. The structure determination of the two IgSF domains and comparison to the N-terminal two-domain structures of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecules (ICAM-1 and ICAM-2) allow us to assess the molecular basis of the interactions between integrins and their preferred ligands. RESULTS: The crystal structure of a fragment containing the two IgSF domains of human MAdCAM-1 has been determined to 2.2 A resolution. The structure of MAdCAM-1 reveals two separate integrin-recognition motifs. The key integrin-binding residue, Asp42, resides in the CD loop of domain 1; a buried arginine residue (Arg70) plays a critical role in maintaining the conformation of this loop. The second binding site is associated with an unusual long D strand in domain 2. The D and E strands extend beyond the main body of the domain, forming a negatively charged beta ribbon unique to MAdCAM-1. This ribbon is located on the same face as the key aspartate residue in domain 1, consistent with evidence that it is involved in integrin binding. CONCLUSIONS: The structural comparison of MAdCAM-1 to other members of the same IgSF subclass reveals some interesting features. Firstly, MAdCAM-1, like VCAM-1, has the key integrin-binding residue located on the protruding CD loop of domain 1 and binds to an integrin that lacks an I domain. This is in contrast to ICAM-1 and ICAM-2 where the key residue is located at the end of the C strand on a flat surface and which bind to integrins that contain I domains. Secondly, architectural differences in the CD loops of MAdCAM-1 and VCAM-1 cause an 8 A shift in position of the critical aspartate residue, and may partly determine their binding preference for different integrins. Finally, the unusual charge distribution of the two-domain fragment of MAdCAM-1 is predicted to orient the molecule optimally for integrin binding on the top of its long mucin-like stalk.
About this Structure
1BQS is a Single protein structure of sequence from Homo sapiens with as ligand. Full crystallographic information is available from OCA.
Reference
The structure of immunoglobulin superfamily domains 1 and 2 of MAdCAM-1 reveals novel features important for integrin recognition., Tan K, Casasnovas JM, Liu JH, Briskin MJ, Springer TA, Wang JH, Structure. 1998 Jun 15;6(6):793-801. PMID:9655832
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