該基因是DNA聚合酶X型家族的一員，編碼一種對寡核苷酸引物的3'-羥基末端添加脫氧核苷酸進行催化的模板無關DNA聚合酶在體內，編碼蛋白在正常和惡性的前b和前t淋巴細胞的限制性群體中在早期分化過程中表達，通過在重組ig重鏈和t細胞受體基因片段的連接處合成非生殖系元素（n區）來產生抗原受體多樣性。另外，還描述了編碼該基因不同亞型的剪接轉錄變體[由RefSeq提供，2008年7月]
This gene is a member of the DNA polymerase type-X family and encodes a template-independent DNA polymerase that catalyzes the addition of deoxynucleotides to the 3'-hydroxyl terminus of oligonucleotide primers. In vivo, the encoded protein is expressed in a restricted population of normal and malignant pre-B and pre-T lymphocytes during early differentiation, where it generates antigen receptor diversity by synthesizing non-germ line elements (N-regions) at the junctions of rearranged Ig heavy chain and T cell receptor gene segments. Alternatively spliced transcript variants encoding different isoforms of this gene have been described. [provided by RefSeq, Jul 2008]