该基因编码的蛋白质是失配修复系统的关键组成部分，其功能是纠正DNA复制和同源重组过程中可能发生的DNA失配、小插入和缺失。该蛋白与mutl同源1（mlh1）基因的基因产物形成异二聚体，形成mutlα异二聚体。mutlα异二聚体具有一种内核溶解活性，在mutsα和mutsβ异二聚体识别不匹配和插入/删除环后被激活，并且是去除不匹配DNA所必需的。在由该基因编码的蛋白质的C端发现一个dqha（x）2e（x）4e基序，该基序构成核酸酶活性位点的一部分。该基因突变与遗传性非息肉性结直肠癌（HNPCC，又称林奇综合征）和Turcot综合征有关。
The protein encoded by this gene is a key component of the mismatch repair system that functions to correct DNA mismatches and small insertions and deletions that can occur during DNA replication and homologous recombination. This protein forms heterodimers with the gene product of the mutL homolog 1 (MLH1) gene to form the MutL-alpha heterodimer. The MutL-alpha heterodimer possesses an endonucleolytic activity that is activated following recognition of mismatches and insertion/deletion loops by the MutS-alpha and MutS-beta heterodimers, and is necessary for removal of the mismatched DNA. There is a DQHA(X)2E(X)4E motif found at the C-terminus of the protein encoded by this gene that forms part of the active site of the nuclease. Mutations in this gene have been associated with hereditary nonpolyposis colorectal cancer (HNPCC; also known as Lynch syndrome) and Turcot syndrome.