UAS regulatory sequences drive expression of the Ugt35C1 coding sequence, amplified from the 'A3' founder strain (relatively susceptible to nicotine). This coding sequence contains a 22bp deletion relative to the sequence from the 'A4' founder strain, leading to a frameshift and a premature stop codon that is predicted to produce a truncated protein of only 206 amino acid residues (compared to 517 in the A4 variant).