gamma:delta T-cell receptors are also generated by gene rearrangement. Some T cells express gamma:delta T-cell receptors rather than alpha:beta T-cell receptors. The organization of the a locus and the d

gamma:delta T-cell receptors are also generated by gene rearrangement. Some T cells express gamma:delta T-cell receptors rather than alpha:beta T-cell receptors. The organization of the a locus and the d locus s to ensure that each T cell cannot express both types of T-cell receptors. The mechanism involved is that: The rearrangement of a T-cell receptor a gene deletes the d locus on that allele. The rearrangement of a T-cell receptor d gene deletes the a locus on that allele. The RAG recombinase enzymes are down-regulated immediately after the first T-cell receptor genes rearrange. The a:b T-cell receptor signals the T cell to delete the d locus. The g:d T-cell receptor signals the T cell to delete the a locus.