Phospholamban (PLN) isan integralmembrane protein that inhibits the sarcoplasmic reticulumCa2+-ATPase, thereby regulating muscle contractility.We report a combined electrochemical and theoretical study demonstrating that the pentameric PLN does not possess channel activity for conducting chloride or calciumions across the lipidmembrane. This suggests that the pentameric configuration of PLN primarily serves as a storage form for the regulatory function of muscle relaxation by the PLN monomer.
Bibliographical noteFunding Information:
This work was supported by grants from the National Institutes of Health to G.V. (GM64742, HL80081, GM072701), D.D.T. (GM27906), J.G. (GM46736), J.G. from the Office of Naval Research, and R.G. from Ente Cassa di Risparmio (Firenze, Italy). All computations were performed on computers at PNNL through an EMSL Grand Challenge grant.