Cloning and expression of the turtle (Trachemys scripta) immunoglobulin joining (J)-chain cDNA

Immunogenetics. 2002 Oct;54(7):513-9. doi: 10.1007/s00251-002-0492-2. Epub 2002 Sep 6.


The J-chain protein is a M(r) 15000 polypeptide associated with polymeric IgA and IgM. The complete cDNA sequences of human, mouse, cow, brushtail possum, chicken and frog J chains have been previously reported, but nothing is known about the cDNA and amino acid sequences of reptilian J chain. Here, we determined a turtle J-chain cDNA sequence by RT-PCR and RACE, and examined J-chain mRNA and protein expression by Northern blotting and immunohistochemistry. This turtle J-chain cDNA was 1934 bp and had an open reading frame of 477 nucleotides, encoding 159 amino acids. The mature J-chain protein is composed of 137 amino acids, M(r) approximately 15000. The deduced amino acid sequence of the turtle J chain was highly homologous to that of human (60%), mouse (61%), cow (60%), rabbit (60%), chicken (69%), brushtail possum (65%), Rana catesbeiana (47%) and Xenopus laevis (58%). Eight cysteine residues were located at the same positions as in these other species, with the exception of X. laevis. PROSITE database analysis indicated the presence of two N-glycosylation sites in turtle, one of which was novel. Northern blot analysis revealed that turtle J-chain mRNA was expressed in lung, stomach, spleen and intestine. In addition, immunohistochemistry showed J-chain-positive plasma cells in the intestine and spleen. These results suggest the presence of a mucosal immune system mainly composed of J-chain-containing Ig in the turtle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blotting, Northern
  • Blotting, Southern
  • DNA
  • Evolution, Molecular
  • Immunoglobulin J-Chains / genetics*
  • Immunohistochemistry
  • Molecular Sequence Data
  • Phylogeny
  • Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Turtles / genetics*
  • Turtles / immunology


  • Immunoglobulin J-Chains
  • DNA

Associated data

  • GENBANK/AB085611