Abstract
Five CD28-like proteins exert positive or negative effects on immune cells. Only four of these five receptors interact with members of the B7 family. The exception is BTLA (B and T lymphocyte attenuator), which instead interacts with the tumor necrosis factor receptor superfamily member HVEM (herpes virus entry mediator). To better understand this interaction, we determined the 2.8-A crystal structure of the BTLA-HVEM complex. This structure shows that BTLA binds the N-terminal cysteine-rich domain of HVEM and employs a unique binding surface compared with other CD28-like receptors. Moreover, the structure shows that BTLA recognizes the same surface on HVEM as gD (herpes virus glycoprotein D) and utilizes a similar binding motif. Light scattering analysis demonstrates that the extracellular domain of BTLA is monomeric and that BTLA and HVEM form a 1:1 complex. Alanine-scanning mutagenesis of HVEM was used to further define critical binding residues. Finally, BTLA adopts an immunoglobulin I-set fold. Despite structural similarities to other CD28-like members, BTLA represents a unique co-receptor.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Binding Sites
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Crystallography, X-Ray
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Humans
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In Vitro Techniques
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Light
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Lymphocytes / immunology
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Models, Molecular
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Molecular Mimicry
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Molecular Sequence Data
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Multiprotein Complexes / chemistry
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Mutagenesis, Insertional
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Protein Structure, Tertiary
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Receptors, Immunologic / chemistry*
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Receptors, Immunologic / genetics
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Receptors, Immunologic / physiology
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Receptors, Tumor Necrosis Factor / chemistry*
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Receptors, Tumor Necrosis Factor / genetics
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Receptors, Tumor Necrosis Factor / physiology
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Receptors, Tumor Necrosis Factor, Member 14
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Receptors, Virus / chemistry*
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Receptors, Virus / genetics
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Receptors, Virus / physiology
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Scattering, Radiation
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Sequence Homology, Amino Acid
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Viral Envelope Proteins / chemistry
Substances
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BTLA protein, human
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Multiprotein Complexes
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Receptors, Immunologic
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Receptors, Tumor Necrosis Factor
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Receptors, Tumor Necrosis Factor, Member 14
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Receptors, Virus
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Recombinant Proteins
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TNFRSF14 protein, human
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Viral Envelope Proteins
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glycoprotein D, Human herpesvirus 1