The G/T binding protein (GTBP, also called MSH6) is a mismatch repair protein that binds as a heterodimer to DNA. GTBP specifically recognizes mismatched G/T base pairs in double-stranded DNA where it triggers excision and repair. Deficiencies in the repair of mismatched G/T base pairs can lead to microsatellite instability and is also linked to hereditary nonpolyposis colon cancer (HNPCC).

