title: Variable domains and a VpreB-like molecule are present in a jawless vertebrate.
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.
authors.affiliation: Department of Molecular Genetics, All Children's Hospital, 801 Sixth Street South, St. Petersburg, FL 33701, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Cannon
authors.forename: Robert N
authors.initials: RN
authors.lastname: Haire
authors.forename: Zeev
authors.initials: Z
authors.lastname: Pancer
authors.forename: M Gail
authors.initials: MG
authors.lastname: Mueller
authors.forename: Diana
authors.initials: D
authors.lastname: Skapura
authors.forename: Max D
authors.initials: MD
authors.lastname: Cooper
authors.forename: Gary W
authors.initials: GW
authors.lastname: Litman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D048428:Petromyzon / Q000235:genetics* / Q000276:immunology*; D054420:Pre-B Cell Receptors; D011947:Receptors, Antigen, B-Cell; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; D007147:Immunoglobulin Light Chains; D054444:Immunoglobulin Light Chains, Surrogate; D007135:Immunoglobulin Variable Region; D008562:Membrane Glycoproteins; D054420:Pre-B Cell Receptors; D011947:Receptors, Antigen, B-Cell