A strong ubiquitin promoter drives expression of a msl-2 cDNA that has been mutated so that the protein carries a R543A amino acid substitution (this point mutation has previously been shown to be essential for DNA binding) and sequence encoding amino acid residues 642-654 has been deleted (this removes the distal part of the Clamp protein-binding domain). The coding sequence is tagged at the C-terminal end with 3xTag:FLAG.