MutL_Trans_MLH3: transducer domain, having a ribosomal S5 domain 2-like fold, found in proteins similar to yeast and human MLH3 (MutL homologue 3). MLH3 belongs to the DNA mismatch repair (MutL/MLH1/PMS2) family. This transducer domain is homologous to the second domain of the DNA gyrase B subunit, which is known to be important in nucleotide hydrolysis and the transduction of structural signals from ATP-binding site to the DNA breakage/reunion regions of the enzymes. MLH1 forms heterodimers with MLH3. The MLH1-MLH3 complex plays a role in meiosis. A role for hMLH1-hMLH3 in DNA mismatch repair (MMR) has not been established. It has been suggested that hMLH3 may be a low risk gene for colorectal cancer; however there is little evidence to support it having a role in classical HNPCC.