This transgene contains the promoter of the mouse beta myosin heavy chain (myosin, heavy polypeptide 7, cardiac muscle, beta) gene, in a ~5.6 kb genomic DNA fragment encompassing upstream sequence and the entire 5-untranslated region (5-UTR) to the translation initiation site in exon 4, driving expression of a 603-bp mouse phospholamban cDNA fragment including 13 bp of the 5-UTR, the full-length protein coding sequence, and 434 bp of the 3-UTR, which is followed by the human growth hormone polyadenylation signal. Immunohistofluorescent analysis of transgenic soleus muscle demonstrated co-localization of PLN and sarcoplasmic reticulum (SR) Ca<2+>-ATPase (SERCA2a), which is responsible for SR Ca<2+> transport in cardiac and slow-twitch (Type I) skeletal muscle fibers. Whereas PLN was undetectable by western blot analysis of wild-type soleas muscle, in transgenic soleas its level relative to that of calsequestrin was ~90% of that observed in cardiac muscle, and the ratio of PLN to SERCA2a was similar between wild-type cardiac and transgenic soleas muscle.