The ~188.5 kbp C57BL/6J mouse bacterial artificial chromosome (BAC) RP23-354N13 was obtained; containing the entire dopamine beta-hydroxylase locus (Dbh), as well as ~106 kbp centromeric flanking sequences (including the complete Adamtsl2 locus) and ~65 kbp telomeric flanking sequences (including the complete Sardh and Sardhos loci). Using homologous recombination/BAC recombineering, a 5640 bp CatCh-IRES-lacZ-pA construct was inserted into the ATG start site of the BAC Dbh gene. No other loci on the BAC were altered. The 11.6 kbp BAC vector (pBA Ce3.6) contained a chloramphenicol selection cassette. Founder line B16-4 was identified with high lacZ expression in the expected cells. The calcium translocating channelrhodopsin cDNA sequence used here encodes the first 309 amino acids of green alga Chlamydomonas reinhardtii channelrhodopsin-2 that has been modified with an L132C amino acid substitution (CTC-to-TGC) designed to cause enhanced Ca2+ permeability.