Structural insights into the evolution of the adaptive immune system: the variable lymphocyte receptors of jawless vertebrates.
Biol Chem
; 391(7): 753-60, 2010 Jul.
Article
em En
| MEDLINE
| ID: mdl-20482318
ABSTRACT
Adaptive immunity in jawless vertebrates is mediated by antigen receptors that are fundamentally different from those of jawed vertebrates. Whereas antibodies and T cell receptors (TCRs) are composed of immunoglobulin (Ig) domains, the variable lymphocyte receptors (VLRs) of jawless fish consist of leucine-rich repeat (LRR) modules. As with antibodies and TCRs, VLRs are assembled by DNA recombination in a process that generates a vast repertoire of receptors. VLRs recognize as diverse an array of particulate and soluble antigens as Ig-based antibodies, and do so with similar affinity and specificity. X-ray crystallographic studies of VLRs in complex with protein and carbohydrate antigens have shown that these LRR-based receptors use nearly all their concave surface to bind ligands, in addition to a highly variable loop in their C-terminal LRR capping module. This structural information, combined with a comprehensive analysis of VLR sequences, has revealed an almost perfect match between antigen-contacting positions and positions with highest sequence diversity. The independent evolution approximately 500 million years ago of LRR-based and Ig-based receptors of comparable diversity and antigen-binding properties provides evidence for the survival value of adaptive immunity in vertebrates.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Linfócitos
/
Receptores Imunológicos
/
Evolução Molecular
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Imunidade Adaptativa
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Sistema Imunitário
Limite:
Animals
Idioma:
En
Revista:
Biol Chem
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Estados Unidos