Evidence for a phosphorylation‐induced conformational change in phospholamban cytoplasmic domain by CD analysis

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Abstract
Phospholamban (PLB), an integral membrane protein of cardiac sarcoplasmic reticulum (SR), is described as the regulator of the Ca2+‐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 Ca2+‐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 phosphorilated 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.