This transgene is derived from the ~260 kb genomic DNA insert of a bacterial artificial chromosome (BAC) clone that contains the coding region and upstream and downstream regulatory elements of the mouse gap junction protein, gamma 1 gene (Gjc1, a.k.a. Cx45). The Gjc1 termination codon has been deleted and its coding sequence joined, in-frame, to the cDNA encoding enhanced green fluorescent protein (EGFP). Southern blot analysis shows that this line (L43) has integrated multiple copies of the transgenic construct. RT-PCR analysis detects the fusion transcript in brain, heart and lung, and immunoblot analysis detects the fusion protein in all three organs at about 2.7-fold the level of the endogenous protein and in similar relative amounts. Immunofluorescent imaging using anti-EGFP and anti-Cx45 polyclonal antibodies demonstrates subcellular co-localization of the fusion and endogenous GJC1/CX45 proteins. Immunoflourescence analysis of fixed tissue sections with anti-EGFP antibodies confirmed and expanded previous expression data for the endogenous gene and demonstrated expression in the atrial and ventricular working myocardium. (J:172341)