UASt regulates expression of full-length, methyltransferase-dead fid coding sequence. The coding sequence contains mutations to critical residues in the methyltransferase domain - specifically, codon 417 (GAG to GCC) and codon 693 (CAC to GCC) to introduce E139A and H231A mutations. (These amino acids correspond to yeast residues D72 and H116, which were identified as critical for methyltransferase function.)