Are RAG1 and RAG2 examples of Horizontal Gene Transfer (HGT) from a prokaryote into a eukayote?

User Question 9: Are RAG1 and RAG2 examples of Horizontal Gene Transfer (HGT) from a prokaryote into a eukayote?

The V(D)J recombination mechanism via the proteins RAG1 and RAG2 is reminiscent of the bacterial tranposases that mediate transposon activity in prokaryotes. This has led some researchers to suggest that RAG1 and RAG2 Are in fact identical to prokaryotic transposases and that they are an example of Horizontal Gene Transfer (HGT) from bacteria into the eukaryotic vertebrate linage, where they have been incorporated into the mechanism behind gene shuffling that Creates the immunoglobulin binding sites that form the basis for the antibody responses In the immune system of higher organisms. How might one test this hypothesis?

In Mapviewer, RAG1 and RAG2 are located at the same overlapping region of Human chromosome 11 but on opposite strands of the chromosomal DNA—an arrangement typical of prokayotic transposases…

• Both RAG1 and RAG2 are examples of "intronless" eukaryotic genes, consistent with a prokaryotic origin
• A search using the Microbial Genomes BLAST shows that the RAG1 and RAG2 DNA sequences are highly similar to known prokaryotic transposases