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Structural Studies on Phospholamban and Implications for Regulation of the Ca 2+ ‐ATPase
Author(s) -
MORTISHIRESMITH RUSSELL J.,
BROUGHTON HOWARD,
GARSKY VICTOR M.,
MAYER ERNEST J.,
JOHNSON ROBERT G.
Publication year - 1998
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1998.tb08257.x
Subject(s) - phospholamban , chemistry , endoplasmic reticulum , circular dichroism , phosphorylation , cytoplasm , biophysics , calcium binding protein , peptide , protein structure , calcium atpase , atpase , protein secondary structure , calcium , biochemistry , biology , enzyme , organic chemistry
The cardiac sarcoplasmic reticulum (SR) protein phospholamban (PLB) is an endogenous inhibitor of the SR Ca 2+ ‐ATPase. Phosphorylation of PLB relieves this inhibition and up‐regulates calcium transport. PLB has proved remarkably difficult to study by conventional solution‐state nuclear magnetic resonance (NMR) methods, due primarily to the extreme hydrophobic nature of the protein and its propensity to form pentamers. That the C‐terminal domain of PLB is helical and membrane spanning is now well established; the structure of the cytoplasmic domain is relatively ill defined. In order to discern the effect of phosphorylation on the structure of the cytoplasmic domain, we have characterized a variety of model peptides in several structure‐inducing and/or lipid‐mimicking environments using circular dichroism and solution‐state NMR. The resolution of peptide structures obtained in aqueous trifluoroethanol was markedly improved by the incorporation of 15 N labels into the peptide backbone, allowing a variety of isotope edited, filtered, and resolved techniques to be applied. Molecular dynamics simulations on the full‐length protein were combined with an analysis of published data to suggest a revised model for the structure of PLB.