Mismatch DNA repair in bacteria is carried out by the MutL, MutH, and MutS proteins. The MutS protein initially binds to mismatched DNA. This is followed by binding of the MutH endonuclease and MutL to form a complex that carries out excision repair. The hMSH2 gene specifies a MutS homologue and hMLH1, hPMS1, and hPMS2 encode MutL homologs. Mutations in these genes are associated with hereditary nonpolyposis colon cancer (HNPCC), one of the most common hereditary diseases in man. As with the bacterial system, HNPCC is characterized by frequent microsatellite mutations that arise by somatic mutation due to a replication error (RER+) phenotype. Both hPMS1 and hPMS2 are mutated in the germline of HNPCC patients. Although the exact function of MutL and its homologs has yet to be determined, it is known that a complex of PMS2 and MLH1 (MutLa) from HeLa cells can complement a deficiency of MLH1 in hypermutable H6 colorectal tumor cells.
DNA mismatch repair protein PMS2; H_DJ0042M02.9; HNPCC4; Mismatch repair endonuclease PMS2; PMS1 homolog 2, mismatch repair protein; PMS1 protein homolog 2; PMS2 postmeiotic segregation increased 2; PMS2CL; PMSL2; postmeiotic segregation increased 2 nirs variant 6