phospholamban Old el New Far eI Near Lin Guo-hua
phospholamban Old & New Far & Near Lin Guo-hua
myocardial Ca2+ T-Tubuli homeostasis SR e SERCA 2a Function: uringsyype Cacam ryano receptor from the Nitrosylation sarcoplasmic reticulum (SR). During diastole Ca is subsequently transported into the SR via the SR SERCA Ca-ATPase(SERCA2a),which is under the inhibitory control of phospholamban (PLB).The intracellular Ca concentration is modified by the sarcolemmal Ca- Aftered or Mu Dominant Ne (e ations in SERCA2a
Schematic representation of myocardial Ca homeostasis. During systole, Ca enters the myocyte over L-type Ca channels (1) and induces a Ca release of the ryanodine receptor from the sarcoplasmic reticulum (SR). During diastole Ca is subsequently transported into the SR via the SR Ca -ATPase (SERCA2a), which is under the inhibitory control of phospholamban (PLB). The intracellular Ca concentration is modified by the sarcolemmal Ca - ATPase (2), the Na /Ca -exchanger (3), the Na , K -ATPase (4), the sarcolemmal Na -channels (5), and the b-adrenoreceptor (6). Diastolic SR Ca movement is modulated through alterations in SERCA2a function and PLB inhibition. myocardial Ca2+ homeostasis
SERCA Phosphorylation Dom eta-Strand Do NH 1001 COOH S2M2 S3M3 M9 10 (Trends Cardiovasc Med 1998;8:330-340)
SERCA (Trends Cardiovasc Med 1998;8:330–340)
Calcium Transport Cycle of Cardiac Sarcoplasmic Reticulum 2CaoATP ADP 个 E 2CaEATP< 2CaEP A ( ① (iv) -2Ca ) E2 E2P H20 Equation shows reaction scheme of Ca translocated by the SERCA enzyme (Trends Cardiovasc Med 1998;8:330-340)
Calcium Transport Cycle of Cardiac Sarcoplasmic Reticulum Equation shows reaction scheme of Ca translocated by the SERCA enzyme (Trends Cardiovasc Med 1998;8:330–340)
(A) (B) (C) PLB PLB. Ablation Overexpression SR SR SR SERCA PLB TIME TIME TIME Schematic representation of phospholamban (PLB)and SR Ca2+-ATPase in native SR membranes firom(A) phospholambandeficient.(B)wild-type,and(C)phospholamban overexpression mice.Phospholamban ablation was associated with increased contractile parameters,while phospholamban overexpression was associated with decreased contractile parameters compared to wild-type mouse hearts. VoL 239,No.1.1997 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Schematic representation of phospholamban (PLB) and SR Ca2+-ATPase in native SR membranes from (A) phospholambandeficient, (B) wild-type, and (C) phospholamban overexpression mice. Phospholamban ablation was associated with increased contractile parameters, while phospholamban overexpression was associated with decreased contractile parameters compared to wild-type mouse hearts. Vol. 239, No. 1, 1997 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
sarcoplasmic sarcoplasmic reticulum reticulum SERCA2 PL SERCA2 Ca2+ Ca2+ kinas cytosol cytosol high Km low Km low Vmax high Vmax Regulation of SERCA2 activity by phospholamban.When unphosphorylated,phospholamban PL binds to SERCA2,raising Km and possibly lowering Vmax.Phosphorylation blocks this interaction and relieves this inhibition.max MA.MoOsesian.RH.G.Research 371998352-359353
Regulation of SERCA2 activity by phospholamban. When unphosphorylated, phospholamban PL binds to SERCA2, raising Km and possibly lowering Vmax . Phosphorylation blocks this interaction and relieves this inhibition. max M.A. MoÕ sesian, R.H.G. SchwingerrCardioÕ ascular Research 37 1998 352–359 353
axeidn+ 8 pCa Schematic representation of the effects of phospholamban on Ca2/-transport in SR vesicles. Phosphorylation of phospholamban(P)is associated with increases in the affinity of SR Ca2+-ATPase for Ca2+compared to nonphosphorylated or control SR vesicles(C).Dephosphorylation of phosphorylated phospholamban is associated with reversal of the stimulatory effects on the Ca2+-affinity of the SR Ca2 ATPase(D). Vol.239,No.1,1997 BIOCHEMICALAND BIOPHYSICALRESEARCH COMMUNICATIONS
Schematic representation of the effects of phospholamban on Ca2/-transport in SR vesicles. Phosphorylation of phospholamban (P) is associated with increases in the affinity of SR Ca2+-ATPase for Ca2+ compared to nonphosphorylated or control SR vesicles (C). Dephosphorylation of phosphorylated phospholamban is associated with reversal of the stimulatory effects on the Ca2+ -affinity of the SR Ca2+ ATPase (D). Vol. 239, No. 1, 1997 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Structural model of the phospholamban monomer monome 1 on A kink of 15-20 occurs in the region of Pro21.The transmembrane domain stretches from Leu52 at the C terminus to roughly Lys27 at the predicted membrane 13 surface.The inset shows the phospholamban helix viewed down the helix axis.The positively charged residues (Arg9,Argl3,Arg25 and Lys27)and the residues which are phosphorylated (Ser16 and Thr17) Head group region lie roughly on one side of the helix.Three Gln residues (Gln22.26 and 29)are predicted to be n29 oriented toward the center of the phospholamban pentamer.The lipid bilayer thickness for liquid rystalline DMPC is shown (heads Acyl chain region ter side interface on the seeorihesR e embrane Head group region Steven O.Smithl et al, 0u52 J.Mol Biol(2001)313,1139-1148
Structural model of the phospholamban monomer Structural model of the phospholamban monomer. Residues 7-52 are modeled as a long a-helix based on polarized infrared and solid-state NMR measurements. A kink of 15-20 occurs in the region of Pro21. The transmembrane domain stretches from Leu52 at the C terminus to roughly Lys27 at the predicted membrane surface. The inset shows the phospholamban helix viewed down the helix axis. The positively charged residues (Arg9, Arg13, Arg25 and Lys27) and the residues which are phosphorylated (Ser16 and Thr17) lie roughly on one side of the helix. Three Gln residues (Gln22, 26 and 29) are predicted to be oriented toward the center of the phospholamban pentamer. The lipid bilayer thickness for liquid crystalline DMPC is shown (headgroup region 9 A and acyl chain region 26 A 43). Leu52 is charged and is predicted to lie at the membrane interface on the lumenal side of the SR membrane. Arg25 and Lys27 are charged and predicted to lie at the membrane interface on the cytoplasmic side of the SR membrane. Steven O. Smith1 et al., J. Mol. Biol. (2001) 313, 1139-1148
Molecular Structure of Phospholamban ⊙&0@ 0⊙@ ⊙00 000 Secondary structure of canine phospholamban 0①③④ ⊙06 monomer.The two a helices,domain la and domain ll,are connected by domain Ib,which form a random structure.Domain I is exposed at the cytoplasmic surface,whereas domain ll is IB anchored in the SR membrane.The circled residues S and T represent Ser16 and Thr17, which are phosphorylated by cAMP-dependent 3 and Ca/calmodulin dependent protein kinase, respectively. 0① ©@ (Trends Cardiovasc Med 1998;8:330-340)
Molecular Structure of Phospholamban (Trends Cardiovasc Med 1998;8:330–340) Secondary structure of canine phospholamban monomer. The two a helices, domain Ia and domain II, are connected by domain Ib, which form a random structure. Domain I is exposed at the cytoplasmic surface, whereas domain II is anchored in the SR membrane. The circled residues S and T represent Ser16 and Thr17, which are phosphorylated by cAMP-dependent and Ca/calmodulin dependent protein kinase, respectively
Models of PLB in the membrane Pro21 The models show the interatomic distance measurements between Pro21-Ala24 and Leu42-Leu44. A which correspond to a helical structure in both regions (inset) Ala24 The structure across the region Ala24-GIn26 (shown in green) Leu42 could not be determined unambiguously and the two models (left and right)show 4.7A extreme structures that are consistent with the measured Leu44 13C-5N interatomic distance (>5 A). JEleri Hughes and David A.Middleton BC Papers in Press Published on January 29,2003 as Manuscript M212208200
Models of PLB in the membrane The models show the interatomic distance measurements between Pro21-Ala24 and Leu42-Leu44, which correspond to a helical structure in both regions (inset). The structure across the region Ala24-Gln26 (shown in green) could not be determined unambiguously and the two models (left and right) show extreme structures that are consistent with the measured 13C-5N interatomic distance (> 5 Å). JEleri Hughes and David A. Middleton BC Papers in Press. Published on January 29, 2003 as Manuscript M212208200