Characterization of cDNA and genomic sequences encoding a chicken phospholamban.

We report on the isolation and characterization of cDNA and genomic sequences encoding a chicken cardiac phospholamban. Three mRNAs, 0.6, 1.1, and 3.3 kilobase pairs in size, were detected in cardiac and slow-tonic muscle RNAs on Northern blots. We determined that these mRNAs differ in the length of their 3'-untranslated regions, perhaps because they utilize alternative polyadenylation signals. We studied the developmental and tissue-specific expression of phospholamban mRNA using nuclease mapping analysis. There appeared to be considerable homology between coding and 3'-untranslated regions of phospholamban mRNAs from cardiac and slow-tonic muscles during development, strongly suggesting that these mRNAs are encoded by the same gene. The phospholamban gene, which is present as a single copy in the chicken genome, is about 10 kilobase pairs long, with approximately 6.5 kilobase pairs representing the intron sequences. Primer extension and nuclease mapping analyses of the 5' end of the phospholamban mRNA showed that the three transcripts are initiated from the same initiation site. Analysis of the putative promoter region revealed "TATA box" and "CAAT box" sequences, putative muscle-specific elements, and a cyclic AMP-responsive element.