Original Paper

Immunogenetics

, Volume 56, Issue 12, pp 924-929

Variable domains and a VpreB-like molecule are present in a jawless vertebrate

  • John P. CannonAffiliated withDepartment of Molecular Genetics, All Children’s HospitalH. Lee Moffitt Cancer Center and Research InstituteDepartment of Pediatrics, USF/ACH Children’s Research Institute, University of South Florida College of Medicine
  • , Robert N. HaireAffiliated withDepartment of Pediatrics, USF/ACH Children’s Research Institute, University of South Florida College of Medicine
  • , Zeev PancerAffiliated withHoward Hughes Medical Institute, University of Alabama at Birmingham
  • , M. Gail MuellerAffiliated withDepartment of Pediatrics, USF/ACH Children’s Research Institute, University of South Florida College of Medicine
  • , Diana SkapuraAffiliated withDepartment of Pediatrics, USF/ACH Children’s Research Institute, University of South Florida College of Medicine
  • , Max D. CooperAffiliated withHoward Hughes Medical Institute, University of Alabama at Birmingham
  • , Gary W. LitmanAffiliated withDepartment of Molecular Genetics, All Children’s HospitalH. Lee Moffitt Cancer Center and Research InstituteDepartment of Pediatrics, USF/ACH Children’s Research Institute, University of South Florida College of Medicine Email author 

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Abstract

Immunoglobulins (Igs) and T cell antigen receptors (TCRs) that undergo somatic diversification have not been identified in the two extant orders of jawless vertebrates, which occupy essential positions in terms of understanding the evolution of the emergence of adaptive immunity. Using a single motif-dependent PCR-based approach coupled with a vector that allows selection of cDNAs encoding secretion signal sequences, four different genes encoding Ig V-type domains were identified in the sea lamprey (Petromyzon marinus). One of the predicted proteins encoded by these genes shares structural characteristics with mammalian VpreB molecules, including the absence of a recognizable transmembrane region, a relatively high proportion of charged amino acids in its C-terminal tail and distinctive features of its secretion signal peptide. This is the first indication of a molecule related to the B cell receptor (BCR) complex in a species that diverged prior to the jawed vertebrates in which RAG-mediated adaptive immunity is first encountered.

Keywords

Jawless vertebrate Lymphocyte ontogeny V-related sequence Phylogeny Immunoglobulin T cell antigen receptor