A TI{KozakGAL4} DNA cassette has been inserted into Pur-α, replacing the coding sequence (coordinates of deleted sequence are 4:560155..565771, release 6 genome). This results in a simultaneous knock-out of Pur-α plus a knock-in of GAL4 that is expected to be expressed under the control of the endogenous regulatory sequences of Pur-α (predicted to gene trap all annotated transcripts of the gene). The TI{KozakGAL4} cassette was inserted via the CRISPR/Cas-9 drop-in technique, using a dsDNA donor vector with homology arms of length 200bp. The sgRNA sequences used to target the gene were: AACTATATGCTGTCGTGTTGAGG and TTATATAACTTAGTAAATCACGG.