Phosphorylation induces a conformational change in the cytoplasmic domain of phospholamban, supporting the mechanism by which it regulates the cardiac Ca(2+)-ATPase pump.
No immediate clinical implications for Ca²⁺ handling; hypothesis-generating for phospholamban-SERCA regulation in vivo.
Phospholamban (PLB), an integral membrane protein of cardiac sarcoplasmic reticulum (SR), is described as the regulator of the Ca(2+)-ATPase pump, via its phosphorylation-dephosphorylation of Ser-16. Recently it has been shown that a direct interaction between the N-terminal hydrophilic domain of PLB and Ca(2+)-ATPase may be one of the mechanisms of regulation. In order to show that this interaction could be modulated by a phosphorylation-induced conformational change in PLB, we ran CD studies on the synthetic peptide PLB(2-33) in its phosphorylated and non-phosphorylated forms, at various pHs, concentrations and in the absence or presence of trifluoroethanol. The results show a clear difference in structure of the phosphorylated and non-phosphorylated peptide.
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Terzi et al. (1992) studied this question.
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