Abstract
The crystal structure of the extracellular domain of CD94, a component of the CD94/NKG2 NK cell receptor, has been determined to 2.6 A resolution, revealing a unique variation of the C-type lectin fold. In this variation, the second alpha helix, corresponding to residues 102-112, is replaced by a loop, the putative carbohydrate-binding site is significantly altered, and the Ca2+-binding site appears nonfunctional. This structure may serve as a prototype for other NK cell receptors such as Ly-49, NKR-P1, and CD69. The CD94 dimer observed in the crystal has an extensive hydrophobic interface that stabilizes the loop conformation of residues 102-112. The formation of this dimer reveals a putative ligand-binding region for HLA-E and suggests how NKG2 interacts with CD94.
MeSH terms
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Amino Acid Sequence
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Antigens, CD / chemistry*
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Antigens, CD / metabolism
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Binding Sites
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Crystallography, X-Ray
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Dimerization
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HLA Antigens / metabolism
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HLA-E Antigens
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Histocompatibility Antigens Class I / metabolism
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Humans
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Killer Cells, Natural / metabolism*
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Lectins / chemistry*
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Lectins / metabolism
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Lectins, C-Type*
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Membrane Glycoproteins / chemistry*
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Membrane Glycoproteins / metabolism
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Models, Molecular
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Molecular Sequence Data
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NK Cell Lectin-Like Receptor Subfamily C
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NK Cell Lectin-Like Receptor Subfamily D
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Protein Folding*
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Receptors, Immunologic / chemistry*
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Receptors, Immunologic / metabolism
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Receptors, Mitogen / chemistry*
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Receptors, Mitogen / metabolism
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Receptors, Natural Killer Cell
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Sequence Homology, Amino Acid
Substances
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Antigens, CD
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HLA Antigens
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Histocompatibility Antigens Class I
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KLRC1 protein, human
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KLRD1 protein, human
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Lectins
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Lectins, C-Type
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Membrane Glycoproteins
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NK Cell Lectin-Like Receptor Subfamily C
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NK Cell Lectin-Like Receptor Subfamily D
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Receptors, Immunologic
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Receptors, Mitogen
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Receptors, Natural Killer Cell