LIG4（DNA ligase 4），癌症关联基因，基因ID：3981，该基因编码的蛋白质是一种DNA连接酶，在ATP依赖的反应中连接双链聚脱氧核苷酸中的单链断裂该蛋白是v（d）j重组和dna双链断裂（dsb）修复的关键。该蛋白与X射线修复交叉互补蛋白4（XRCC4）形成复合物，并进一步与DNA依赖性蛋白激酶（DNA-PK）相互作用已知NHEJ需要XRCC4和DNA-PK。该蛋白与XRCC4形成的配合物的晶体结构已被解析。该基因缺陷是LIG4综合征的病因另外，还观察到编码相同蛋白质的剪接转录变体[由RefSeq提供，2008年7月]The protein encoded by this gene is a DNA ligase that joins single-strand breaks in a double-stranded polydeoxynucleotide in an ATP-dependent reaction. This protein is essential for V(D)J recombination and DNA double-strand break (DSB) repair through nonhomologous end joining (NHEJ). This protein forms a complex with the X-ray repair cross complementing protein 4 (XRCC4)， and further interacts with the DNA-dependent protein kinase (DNA-PK). Both XRCC4 and DNA-PK are known to be required for NHEJ. The crystal structure of the complex formed by this protein and XRCC4 has been resolved. Defects in this gene are the cause of LIG4 syndrome. Alternatively spliced transcript var。