Probable helicase, member of the UBC2/RAD6 epistasis group. Functions with the DNA repair protein RAD18 in error-free postreplication DNA repair. Involved in the maintenance of wild-type rates of instability of simple repetitive sequences such as poly(GT) repeats. Seems to be involved in maintaining a balance which acts in favor of error-prone non-homologous joining during DNA double-strand breaks repairs. Recruits the UBC13-MMS2 dimer to chromatin for DNA repair. Optimum pH is 7.0. for ATPase activity. Homodimer. Interacts with POL30, RAD18, UBC9 and UBC13. Present with 1520 molecules/cell in log phase SD medium. Belongs to the SNF2/RAD54 helicase family.