MutS Homolog 2 (MSH2)

MSH2 was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). When cloned, it was discovered to be a human homolog of the E. coli mismatch repair gene mutS, consistent with the characteristic alterations in microsatellite sequences (RER+ phenotype) found in HNPCC. It is also associated with some endometrial cancers.

MSH2 is homologous to a prokaryotic gene, MutS, that participates in mismatch repair. The highest homology is to the yeast Msh2 gene in the helix-turn-helix domain, perhaps responsible for MutS binding to DNA. The yeast and human Msh2 proteins are 77% identical between codons 615 and 788. There are 10 other blocks of similar amino acids distributed throughout the length of the 2 proteins.