On the function of pentameric phospholamban: ion channel or storage form?
نویسندگان
چکیده
Phospholamban (PLN) is an integral membrane protein that inhibits the sarcoplasmic reticulum Ca(2+)-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 calcium ions across the lipid membrane. 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.
منابع مشابه
Structural model of the phospholamban ion channel complex in phospholipid membranes.
Phospholamban is a 52 amino acid residue membrane protein involved with the regulation of calcium levels across sarcoplasmic reticulum membranes in cardiac muscle cells. The N-terminal 30 amino acid residues of the protein are largely hydrophilic and include two sites whose phosphorylation is thought to dissociate an inhibitory complex between phospholamban and Ca2+ ATPase. The C-terminal 22 am...
متن کاملStructural topology of phospholamban pentamer in lipid bilayers by a hybrid solution and solid-state NMR method.
Phospholamban (PLN) is a type II membrane protein that inhibits the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), thereby regulating calcium homeostasis in cardiac muscle. In membranes, PLN forms pentamers that have been proposed to function either as a storage for active monomers or as ion channels. Here, we report the T-state structure of pentameric PLN solved by a hybrid solution and solid-s...
متن کاملPhosphorylation and mutation of phospholamban alter physical interactions with the sarcoplasmic reticulum calcium pump.
Phospholamban physically interacts with the sarcoplasmic reticulum calcium pump (SERCA) and regulates contractility of the heart in response to adrenergic stimuli. We studied this interaction using electron microscopy of 2D crystals of SERCA in complex with phospholamban. In earlier studies, phospholamban oligomers were found interspersed between SERCA dimer ribbons and a 3D model was construct...
متن کاملEffects of phospholipids on the oligomeric state of phospholamban of the cardiac sarcoplasmic reticulum.
BACKGROUND Phospholamban is a reversible inhibitor of the Ca(2+)-ATPase of the cardiac sarcoplasmic reticulum (SR) and contributes to the regulation of heart muscle contractility. Because only the monomeric form, not the pentameric form, of phospholamban inhibits the Ca2+-pumping activity of the SR, it is important to understand the dynamic equilibrium between these 2 forms. METHODS AND RESUL...
متن کاملInteractions between Ca-ATPase and the pentameric form of phospholamban in two-dimensional co-crystals
Phospholamban (PLB) physically interacts with Ca 2+-ATPase and regulates contractility of the heart. We have studied this interaction using electron microscopy of large two-dimensional co-crystals of Ca 2+-ATPase and the I40A mutant of PLB. Crystallization conditions were derived from those previously used for thin, helical crystals, but the addition of a 10-fold higher concentration of magnesi...
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ورودعنوان ژورنال:
- Biophysical journal
دوره 96 10 شماره
صفحات -
تاریخ انتشار 2009