A KDRT stop cassette (which also contains a single loxP site), followed by a Tag:ALFA epitope tag that is flanked by GS linkers, has been inserted into the endogenous 5-HT1A locus in the third intracellular loop. This results in a conditionally tagged allele; KDR recombinase can be used to excise the KDRT cassette to produce Tag:ALFA-tagged 5-HT1A.