Comparative analysis of phospholamban phosphorylation in crude membranes of vertebrate hearts

Phospholamban, a sarcoplasmic reticulum phosphoprotein, is present in the hearts of mammalian, avian, amphibian, and fish species. Phylogenetic changes are indicated by marked differences among species in cardiac phospholamban content and by the absence of Ca2+/calmodulin-dependent phospholamban phosphorylation at an early developmental stage.