What is the function of the enzyme TdT in the immune system?

The enzyme terminal deoxynucleotidyl transferase (TdT) plays a crucial role in the immune system by adding nucleotides to the ends of a DNA strand during the process of recombination. This is particularly important in the development of B and T lymphocytes, where diverse antigen receptors are generated. During V(D)J recombination, TdT facilitates the addition of N nucleotides at the junctions of V, D, and J gene segments. This mechanism increases the diversity of the antigen receptors, allowing the immune system to recognize a wide range of pathogens.

By adding these nucleotides, TdT contributes to the variability that is essential for the proper functioning of adaptive immunity. This variability enables the immune system to adapt and respond to various antigens effectively. Hence, understanding the role of TdT provides insight into how the immune system develops the ability to recognize a vast array of pathogens through recombination processes.