Variable domains and a VpreB-like molecule are present in a jawless vertebrate.
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.
Cannon
John P
JP
Department of Molecular Genetics, All Children's Hospital, 801 Sixth Street South, St. Petersburg, FL 33701, USA.
Haire
Robert N
RN
Pancer
Zeev
Z
Mueller
M Gail
MG
Skapura
Diana
D
Cooper
Max D
MD
Litman
Gary W
GW
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
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