Identification and characterisation of a homolog of an activation gene for the recombination activating gene 1 (RAG 1) in amphioxus.
Expression of recombination activating genes (RAG) involved in the V (D) J recombination is regulated by the RAG1 gene activator (RGA) in mammals. The sequence of a cDNA clone from an amphioxus cDNA library was found to be homologous to that of RGA from mouse stromal cells with 45% identity. The full-length cDNA sequence comprises 1119 bp and encodes a putative protein of 210 amino acid residues. Characterisation of the amino acid sequence revealed that two MtN3 domains and seven transmembrane spans are present in this protein, indicating a potential role as a plasma membrane protein. This gene is expressed in many tissues and at differential developmental stages. A high expression level of RGA is detected in gonad tissues, and gastrula embryo and adult stages. The presence of the RGA gene in amphioxus suggests that the signal pathway required for the expression of RAG could exist in this primitive protochordate. It also implies that in the related molecules, primitive adaptive immunity may have existed in cephalochordate although the complete machinery of VDJ rearrangement may not be formed.
Dong
Meiling
M
Department of Biochemistry, State Open Laboratory for Marine Function Genomics, Guangzhou Center for Bioinformatics, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275, PR China.
Fu
Yonggui
Y
Yu
Cuiling
C
Su
Jing
J
Huang
Shengfeng
S
Wu
Xiaokun
X
Wei
Jianwen
J
Yuan
Shaochun
S
Shen
Yang
Y
Xu
Anlong
A
D000595:Amino Acid Sequence; D000818:Animals; D000917:Antibody Formation / Q000235:genetics; D001483:Base Sequence; D015139:Blotting, Southern; D002681:China; D002816:Chordata, Nonvertebrate / Q000235:genetics* / Q000276:immunology; D016000:Cluster Analysis; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D015723:Gene Library; D016654:Genes, RAG-1 / Q000502:physiology; D005809:Genes, Regulator / Q000235:genetics* / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics
D017931:DNA Primers; D018076:DNA, Complementary; D008565:Membrane Proteins