該基因編碼的蛋白質是失配修復系統的關鍵組成部分，其功能是糾正DNA復制和同源重組過程中可能發生的DNA失配、小插入和缺失。該蛋白與mutl同源1（mlh1）基因的基因產物形成異二聚體，形成mutlα異二聚體。mutlα異二聚體具有一種內核溶解活性，在mutsα和mutsβ異二聚體識別不匹配和插入/刪除環后被激活，并且是去除不匹配DNA所必需的。在由該基因編碼的蛋白質的C端發現一個dqha（x）2e（x）4e基序，該基序構成核酸酶活性位點的一部分。該基因突變與遺傳性非息肉性結直腸癌（HNPCC，又稱林奇綜合征）和Turcot綜合征有關。
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.