The transgene contains a full length mouse cardiac phospholamban cDNA with a point mutation (ACT->GCT) that encodes alanine instead of threonine at amino acid position 17 of the protein (T17A), followed by an SV40 polyadenylation signal, under control of the cardiac specific alpha myosin heavy chain (myosin, heavy polypeptide 6, cardiac muscle, alpha) promoter. The replaced threonine normally is phosphorylated in response to stimulation of cardiac muscle beta adrenergic receptors. Northern blot analysis revealed cardiac expression of the 1.0 kb transcript from the transgene, and quantitative immunoblot analysis demonstrated expression of phospholamban protein in the hearts of transgenic mice homozygous for a null phospholamban allele.