There are five highly conserved Msh members (Msh2-Msh6) but only Msh2, Msh3 and Msh6 have been shown to be involved in mismatch repair. Evidence for Msh4 and Msh5 in MMR is lacking but they are believed to be involved in meiotic recombination. Mammals have two MutS activities: the alpha activity is represented by Msh2-Msh6 heterodimer while beta is represented by Msh2-Msh3 heterodimer. Msh members involved in MMR are listed with aliases in parentheses, full name and link to gene report pages (there is no Msh6 rat gene in the database, the link is to the human gene):

Msh2 – MutS homolog 2 (E. coli)
Msh3 – MutS homolog 3 (E. coli)
MSH6 – MutS homolog 6 (E. coli)