Sequence for a Gly-Ser-Gly spacer, a OneâSTrEPâtag (OST), two STOP codons, an IRES2 sequence, a Kozak sequence, a sequence coding for the monomeric cyan (teal) fluorescent reporter gene mTFP1, a loxP site, and an FRT site flanked neomycin resistance gene cassette, was inserted in-frame at the 3â² end of the gene coding sequence exon 19. A second loxP site was inserted into intron 18. The neo cassette was removed through subsequent Flp-mediated recombination. The fusion of the OST to the protein can be used in affinity purification.