Moieties of Complement iC3b Recognized by the I-domain of Integrin αXβ2
Autor: | Jeongsuk Choi, Sang-Uk Nham, Dolgorsuren Buyannemekh |
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Rok vydání: | 2020 |
Předmět: |
I-domain
Stereochemistry αMβ2 Integrin binding sites protein-protein interactions Integrin alphaXbeta2 Complement receptor Complement factor I Protein–protein interaction law.invention iC3b 03 medical and health sciences αXβ2 0302 clinical medicine law parasitic diseases Humans complement Amino Acid Sequence Binding site Molecular Biology Opsonin 030304 developmental biology 0303 health sciences biology Chemistry Cell Biology General Medicine Protein Structure Tertiary Complement C3b biology.protein Recombinant DNA integrins 030217 neurology & neurosurgery Protein Binding Research Article |
Zdroj: | Molecules and Cells |
ISSN: | 0219-1032 |
Popis: | Complement fragment iC3b serves as a major opsonin for facilitating phagocytosis via its interaction with complement receptors CR3 and CR4, also known by their leukocyte integrin family names, αMβ2 and αXβ2, respectively. Although there is general agreement that iC3b binds to the αM and αX I-domains of the respective β2-integrins, much less is known regarding the regions of iC3b contributing to the αX I-domain binding. In this study, using recombinant αX I-domain, as well as recombinant fragments of iC3b as candidate binding partners, we have identified two distinct binding moieties of iC3b for the αX I-domain. They are the C3 convertase-generated N-terminal segment of the C3b α'- chain (α'NT) and the factor I cleavage-generated N-terminal segment in the CUBf region of α-chain. Additionally, we have found that the CUBf segment is a novel binding moiety of iC3b for the αM I-domain. The CUBf segment shows about a 2-fold higher binding activity than the α'NT for αX I-domain. We also have shown the involvement of crucial acidic residues on the iC3b side of the interface and basic residues on the I-domain side. |
Databáze: | OpenAIRE |
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