Five tandem copies of the Tag:V5 epitope have been inserted into the endogenous mGluR locus, near the C-terminal end of the coding sequence. A KDRT-STOP-KDRT cassette has also been inserted, just upstream of the last mGluR coding exon (the cassette is upstream of the Tag:V5 tag); this was designed to allow conditional expression of Tag:V5-tagged mGluR protein, however the Tag:V5-tagged mGluR protein is constitutively expressed, presumably due to the STOP cassette being ineffective.