title: Isolation of a shark immunoglobulin light chain cDNA clone encoding a protein resembling mammalian kappa light chains: implications for the evolution of light chains.
abstract: The time of emergence of immunoglobulin kappa and lambda light (L) chains in evolution is unknown. An L chain cDNA clone was isolated from the nurse shark (Ginglymostoma cirratum), a cartilaginous fish, whose predicted variable (V) region amino acid sequence has up to 60% sequence identity to mammalian V kappa domains. Genomic analyses suggest a cluster-type gene organization for this L chain locus, similar to the shark lambda-like immunoglobulin L chain loci rather than mammalian kappa loci. We propose that divergence of the ancestral L chain into isotypes likely occurred before the emergence of elasmobranchs 400-450 million years ago. Similarities in gene organization between the two isotypes in sharks may reflect the gene organization utilized by the ancestral L chain.
authors.affiliation: Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101.
authors.forename: A S
authors.initials: AS
authors.lastname: Greenberg
authors.forename: L
authors.initials: L
authors.lastname: Steiner
authors.forename: M
authors.initials: M
authors.lastname: Kasahara
authors.forename: M F
authors.initials: MF
authors.lastname: Flajnik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D015139:Blotting, Southern; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000235:genetics; D005803:Genes, Immunoglobulin; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012754:Sharks / Q000235:genetics*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D007147:Immunoglobulin Light Chains