A Ubiquitin promoter drives expression of the mGluR coding sequence that is tagged at the N-terminal end with Tag:FLAG and at the C-terminal end with 3xVHH05-tag. The codon usage of the mGluR coding sequence has been modified (by synonymous codon substitutions) so that the codons correspond to the most commonly used synonymous codon in the D. melanogaster genome, except where most of the orb2 binding sites in the mRNA are, which have the codons of the endogenous sequence, resulting in 26 orb2 binding sites being present in the mRNA.