Recombination activating gene 1 also known as RAG-1 is a protein that in humans is encoded by the RAG1gene.
The protein encoded by this gene is involved in activation of immunoglobulin V-D-J recombination. The encoded protein is involved in recognition of the DNA substrate, but stable binding and cleavage activity also requires RAG2. The RAG-1/2 complex recognizes the Recombination Signal Sequence (RSS) that flank the V, D and J regions in the gene that codes for the constant region of both the heavy chain and light chain in an antibody. The complex binds to the Recombination Signal Sequences and nicks the DNA. This leads to the removal of the RSS and the eventual binding of the V D and J sequences. Defects in this gene can be the cause of several diseases.