Phospholamban pentamer

ZLL), looking down on the central cavity, (h) Side view of the phospholamban pentamer shown in (g) overlaid with a refined version of the structure published in 2006 (PDB ID 2HYN). 

Roosild TP, Greenwald J, Vega M, Castronovo S, Riek R, Choe S. NMR structure of Mistic, a membrane-integrating protein for membrane protein expression. Science 2005 307 1317-1321. Oxenoid K, Chou JJ. The structure of phospholamban pentamer reveals a channel-like architecture in membranes. Proc. Natl. Acad. Sci. U.S.A. 2005 102 10870-10875. 

Determining the Structure of the Phospholamban Pentamer by Homo FRET... 

S. Robia, N. Flohr, D. Thomas, Phospholamban pentamer quaternary conformation determined by in-gel fluorescence anisotropy, Biochemistry 2005, 44,4302-4311. 

Oxenoid K, Chou JJ (2005) The structure of phospholamban pentamer reveals a channel-like architecture in membranes. Proc Natl Acad Sci USA 102 10870-10875... 

K. Oxenoid, A.J. Rice, J.J. Chou, Comparing the structure and dynamics of phospholamban pentamer in its unphosphorylated and pseudo-phosphorylated states. Protein Sci. 16 (2007) 1977-1983. 

Phospholamban is a homopentameric membrane protein involved in muscle contraction through regulation of the calcium pump in cardiac muscle cells. The stmcture of the unphospho-rylated protein solved in DPC micelles reveals a symmetric pentamer of phospholamban monomers (Fig. 2g) stabilized by leucine/isoleucine zipper motifs along the transmembrane domains (51). Notably, another stmcture was produced for phospholamban (Fig. 2h) that used a variant of the traditional simulated annealing and molecular dynamics protocol that reduced the chances of entrapment in local minima (52). 

Phospholamban was initially detected in smooth muscle in purified ER preparations from pig stomach and rabbit aorta as electrophoretic bands comigrating with the 25-kDa pentameric and 5-kDa monomeric forms of cardiac phospholamban. The dissociation of the pentamer depends on the conditions of pretreatment of the sample with the denaturing electrophoresis buffer. Phospholamban protein has also been detected in many other vascular and gastrointestinal smooth muscles, including rat aortic cells (Sarcevic et al, 1989 Karczewski et ai, 1992), canine ileum and iliac artery (Ferguson et al., 1988), and bovine aorta (L. Raeymaekers, unpublished observations Watras,... 

Phospholamban (PEN) is a single-pass 52-amino acid membrane protein that interacts with the Ca-ATPase (SERCA) in cardiac muscle. Wild-type PEN, existing as a pentamer, takes the pinwheel topology as the predominant conformation with the cytoplasmic domain interacting with the membrane surface [262—264]. The PEN monomer (AFA-PEN), in which three TM cysteines are replaced by A36, F41 and A46, is functionally active and in equilibrium between ordered (T) and disordered (R) states [265,266] N backbone and Ile-methyl dispersion data indicate that residues within domain la (residues 1-16), the loop (17-22), and domain lb (23-30) of PEN undergo is-ms dynamics (feex=6100 800 s at 17 °C) [267]. 

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