{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Terminal Deoxynucleotidyl Transferase (also known as TdT or terminal transferase) is a specialized DNA polymerase expressed in cortical thymocytes and primitive lymphocytes (pre-B and pre-T lymphoid cells). TdT catalyzes the addition of nucleotides to the 3’ terminus of a DNA molecule. Unlike most DNA polymerases, it does not require a template. The preferred substrate of this enzyme is a protruding 3’ overhang, but it can also add nucleotides to blunt or recessed 3’ ends. TdT is found in the nucleus of normal hematopoietic cells, normal cortical thymocytes and in the cytoplasm of megakaryocytes of the bone marrow."}]}]}