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PDBsum entry 3m19
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Immune system
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PDB id
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3m19
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References listed in PDB file
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Key reference
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Title
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A structural basis for antigen recognition by the t cell-Like lymphocytes of sea lamprey.
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Authors
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L.Deng,
C.A.Velikovsky,
G.Xu,
L.M.Iyer,
S.Tasumi,
M.C.Kerzic,
M.F.Flajnik,
L.Aravind,
Z.Pancer,
R.A.Mariuzza.
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Ref.
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Proc Natl Acad Sci U S A, 2010,
107,
13408-13413.
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PubMed id
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Abstract
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Adaptive immunity in jawless vertebrates is mediated by leucine-rich repeat
proteins called "variable lymphocyte receptors" (VLRs). Two types of VLR (A and
B) are expressed by mutually exclusive lymphocyte populations in lamprey. VLRB
lymphocytes resemble the B cells of jawed vertebrates; VLRA lymphocytes are
similar to T cells. We determined the structure of a high-affinity VLRA isolated
from lamprey immunized with hen egg white lysozyme (HEL) in unbound and
antigen-bound forms. The VLRA-HEL complex demonstrates that certain VLRAs, like
gammadelta T-cell receptors (TCRs) but unlike alphabeta TCRs, can recognize
antigens directly, without a requirement for processing or antigen-presenting
molecules. Thus, these VLRAs feature the nanomolar affinities of antibodies, the
direct recognition of unprocessed antigens of both antibodies and gammadelta
TCRs, and the exclusive expression on the lymphocyte surface that is unique to
alphabeta and gammadelta TCRs.
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