title: Antigen recognition by variable lymphocyte receptors.
abstract: Variable lymphocyte receptors (VLRs) rather than antibodies play the primary role in recognition of antigens in the adaptive immune system of jawless vertebrates. Combinatorial assembly of leucine-rich repeat (LRR) gene segments achieves the required repertoire for antigen recognition. We have determined a crystal structure for a VLR-antigen complex, VLR RBC36 in complex with the H-antigen trisaccharide from human blood type O erythrocytes, at 1.67 angstrom resolution. RBC36 binds the H-trisaccharide on the concave surface of the LRR modules of the solenoid structure where three key hydrophilic residues, multiple van der Waals interactions, and the highly variable insert of the carboxyl-terminal LRR module determine antigen recognition and specificity. The concave surface assembled from the most highly variable regions of the LRRs, along with diversity in the sequence and length of the highly variable insert, can account for the recognition of diverse antigens by VLRs.
authors.affiliation: Department of Molecular Biology, Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Byung Woo
authors.initials: BW
authors.lastname: Han
authors.forename: Brantley R
authors.initials: BR
authors.lastname: Herrin
authors.forename: Max D
authors.initials: MD
authors.lastname: Cooper
authors.forename: Ian A
authors.initials: IA
authors.lastname: Wilson
mesh_terms: D000017:ABO Blood-Group System / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007798:Lampreys / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011946:Receptors, Antigen / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D014312:Trisaccharides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism
chemical_list: D000017:ABO Blood-Group System; D011946:Receptors, Antigen; D014312:Trisaccharides