title: Identification of a third variable lymphocyte receptor in the lamprey.
abstract: Jawless vertebrates such as lamprey and hagfish lack T-cell and B-cell receptors; instead, they have unique antigen receptors known as variable lymphocyte receptors (VLRs). VLRs generate diversity by recombining highly diverse leucine-rich repeat modules and are expressed clonally on lymphocyte-like cells (LLCs). Thus far, two types of receptors, VLRA and VLRB, have been identified in lampreys and hagfish. Recent evidence indicates that VLRA and VLRB are expressed on distinct populations of LLCs that resemble T cells and B cells of jawed vertebrates, respectively. Here we identified a third VLR, designated VLRC, in the lamprey. None of the approximately 100 VLRC cDNA clones subjected to sequencing had an identical sequence, indicating that VLRC can generate sufficient diversity to function as antigen receptors. Notably, the C-terminal cap of VLRC exhibits only limited diversity and has important structural differences relative to VLRA and VLRB. Single-cell PCR analysis identified LLCs that rearranged VLRC but not VLRA or VLRB, suggesting the presence of a unique population of LLCs that express only VLRC.
authors.affiliation: Department of Pathology, Hokkaido University Graduate School of Medicine, 060-8638 Sapporo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kasamatsu
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sutoh
authors.forename: Kazunori
authors.initials: K
authors.lastname: Fugo
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Otsuka
authors.forename: Kazuya
authors.initials: K
authors.lastname: Iwabuchi
authors.forename: Masanori
authors.initials: M
authors.lastname: Kasahara
mesh_terms: D000818:Animals; D018076:DNA, Complementary; D015321:Gene Rearrangement; D008969:Molecular Sequence Data; D048428:Petromyzon / Q000276:immunology*; D011946:Receptors, Antigen / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D018076:DNA, Complementary; D011946:Receptors, Antigen