The construct was designed with (from 5' to 3') a CMV-IE enhancer/chicken beta-actin/rabbit beta-globin hybrid promoter (CAG), an FRT site, a loxP-flanked STOP cassette (with stop codons in all 3 reading frames and a triple polyA signal), a hemagglutinin epitope tag (HA), the hM3Dq sequence, a porcine teschovirus (PTA) cleavage site, the mCitrine fluorescent protein, a woodchuck hepatitis virus post-transcriptional regulatory element (WPRE; to enhance the mRNA transcript stability), a BGH polyA signal, and an attB/attP-flanked PGK-FRT-Neo-polyA cassette. The hM3Dq sequence is a Gq-coupled human M3 muscarinic DREADD (designer receptor exclusively activated by designer drug). To create the hM3Dq sequence, the wildtype human muscarinic 3 receptor (CHRM3) sequence was modified via site-directed mutagenesis to harbor two amino acid substitutions (Y149C<3.33>/A239G<5.46>) that abolish receptor affinity for the native ligand, acetylcholine (ACh), but allow receptor binding and subsequent activation by the small drug-like molecule clozapine-N-oxide (CNO). Citrine is a yellow-green variant of Citrine YFP additionally harboring the A206K mutation. mCitrine is a ~5.7 pKa monomer with 516nm excitation and 529nm emmission spectra. Compared to wildtype GFP, Citrine harbors the S65G, V68L, Q69M, S72A and T203Y mutations, and mCitrine additionally has the A206K mutation (enhancing its ability to be a stable monomer). Aanalysis of the transgene integration site at The Jackson Laboratory revealed a single (or partial) transgene copy integrated on chromosome 14 (chr14:41,019,438-41,024,312 [mm10]) in a manner suggestive of complex structural variation surrounding the integration site. Specifically, there is duplication of nearby genome sequences involving the genes Tspan14, Prxl2a, Dydc2, Dydc1, Mat1a, Sftpa1 and Mbl1 (J:236327)
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