MLH1 is an integral component of the DNA mismatch repair (MMR) system that functions to recognize aberrant structures and signals for the repair of single base mismatches or loops in replicated DNA. MLH1 can heterodimerize with DNA mismatch repair protein MLH3 and with mismatch repair endonuclease PMS2. [taken from NCBI Entrez Gene (Gene ID: 4292)].