Logo of biochemjBJ Latest papers and much more!
Biochem J. Feb 1, 1988; 249(3): 709–714.
PMCID: PMC1148764

Phosphorylation of C-protein, troponin I and phospholamban in isolated rabbit hearts.

Abstract

Phosphorylation of myofibrillar and sacroplasmic-reticulum (SR) proteins was studied in Langendorff-perfused rabbit hearts subjected to various inotropic interventions. Stimulation of hearts with isoprenaline resulted in the phosphorylation of both troponin I (TnI) and C-protein in myofibrils and phospholamban in SR. Phosphorylation of phospholamban could be reversed by a 15 min perfusion with drug-free buffer, after a 1 minute pulse perfusion with isoprenaline, at which time the mechanical effects of isoprenaline stimulation had also been reversed. However, both TnI and C-protein remained phosphorylated at this time. Moreover, the inhibition of Ca2+ activation of the Mg2+-dependent ATPase (Mg-ATPase) activity associated with myofibrillar phosphorylation persisted in myofibrils prepared from hearts frozen after 15 min of washout of isoprenaline. To assess the contribution of C-protein phosphorylation in the decrease of Ca2+ activation of the myofibrillar Mg-ATPase activity, we reconstituted a regulated actomyosin system in which only C-protein was phosphorylated. In this system, C-protein phosphorylation did not contribute to the decrease in Ca2+ activation of Mg-ATPase activity, indicating that TnI phosphorylation is responsible for the diminished sensitivity of the myofibrils to Ca2+. These observations support the hypothesis that phospholamban phosphorylation plays a more dominant role than TnI or C-protein phosphorylation in the mechanical response of the mammalian heart to beta-adrenergic stimulation.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.2M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Images in this article

Click on the image to see a larger version.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Bailin G. Phosphorylation of a bovine cardiac actin complex. Am J Physiol. 1979 Jan;236(1):C41–C46. [PubMed]
  • Blanchard EM, Solaro RJ. Inhibition of the activation and troponin calcium binding of dog cardiac myofibrils by acidic pH. Circ Res. 1984 Sep;55(3):382–391. [PubMed]
  • Carter SG, Karl DW. Inorganic phosphate assay with malachite green: an improvement and evaluation. J Biochem Biophys Methods. 1982 Dec;7(1):7–13. [PubMed]
  • Craig R, Offer G. The location of C-protein in rabbit skeletal muscle. Proc R Soc Lond B Biol Sci. 1976 Mar 16;192(1109):451–461. [PubMed]
  • England PJ. Correlation between contraction and phosphorylation of the inhibitory subunit of troponin in perfused rat heart. FEBS Lett. 1975 Jan 15;50(1):57–60. [PubMed]
  • Fabiato A, Fabiato F. Calculator programs for computing the composition of the solutions containing multiple metals and ligands used for experiments in skinned muscle cells. J Physiol (Paris) 1979;75(5):463–505. [PubMed]
  • Hartzell HC. Phosphorylation of C-protein in intact amphibian cardiac muscle. Correlation between 32P incorporation and twitch relaxation. J Gen Physiol. 1984 Apr;83(4):563–588. [PMC free article] [PubMed]
  • Hartzell HC. Effects of phosphorylated and unphosphorylated C-protein on cardiac actomyosin ATPase. J Mol Biol. 1985 Nov 5;186(1):185–195. [PubMed]
  • Hartzell HC, Titus L. Effects of cholinergic and adrenergic agonists on phosphorylation of a 165,000-dalton myofibrillar protein in intact cardiac muscle. J Biol Chem. 1982 Feb 25;257(4):2111–2120. [PubMed]
  • Holroyde MJ, Small DA, Howe E, Solaro RJ. Isolation of cardiac myofibrils and myosin light chains with in vivo levels of light chain phosphorylation. Biochim Biophys Acta. 1979 Nov 1;587(4):628–637. [PubMed]
  • Jeacocke SA, England PJ. Phosphorylation of a myofibrillar protein of Mr 150 000 in perfused rat heart, and the tentative indentification of this as C-protein. FEBS Lett. 1980 Dec 15;122(1):129–132. [PubMed]
  • Katz AM. Role of the contractile proteins and sarcoplasmic reticulum in the response of the heart to catecholamines: an historical review. Adv Cyclic Nucleotide Res. 1979;11:303–343. [PubMed]
  • Kranias EG. Regulation of calcium transport by protein phosphatase activity associated with cardiac sarcoplasmic reticulum. J Biol Chem. 1985 Sep 15;260(20):11006–11010. [PubMed]
  • Kranias EG, Solaro RJ. Phosphorylation of troponin I and phospholamban during catecholamine stimulation of rabbit heart. Nature. 1982 Jul 8;298(5870):182–184. [PubMed]
  • Kranias EG, Mandel F, Wang T, Schwartz A. Mechanism of the stimulation of calcium ion dependent adenosine triphosphatase of cardiac sarcoplasmic reticulum by adenosine 3',5'-monophosphate dependent protein kinase. Biochemistry. 1980 Nov 11;19(23):5434–5439. [PubMed]
  • Kranias EG, Garvey JL, Srivastava RD, Solaro RJ. Phosphorylation and functional modifications of sarcoplasmic reticulum and myofibrils in isolated rabbit hearts stimulated with isoprenaline. Biochem J. 1985 Feb 15;226(1):113–121. [PMC free article] [PubMed]
  • Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. [PubMed]
  • Lehman W. Thick-filament-linked calcium regulation in vertebrate striated muscle. Nature. 1978 Jul 6;274(5666):80–81. [PubMed]
  • Lindemann JP, Watanabe AM. Muscarinic cholinergic inhibition of beta-adrenergic stimulation of phospholamban phosphorylation and Ca2+ transport in guinea pig ventricles. J Biol Chem. 1985 Oct 25;260(24):13122–13129. [PubMed]
  • Metzger H, Lindner E. The positive inotropic-acting forskolin, a potent adenylate cyclase activator. Arzneimittelforschung. 1981;31(8):1248–1250. [PubMed]
  • Mope L, McClellan GB, Winegrad S. Calcium sensitivity of the contractile system and phosphorylation of troponin in hyperpermeable cardiac cells. J Gen Physiol. 1980 Mar;75(3):271–282. [PMC free article] [PubMed]
  • Nakamura J, Wang T, Tsai LI, Schwartz A. Properties and characterization of a highly purified sarcoplasmic reticulum Ca2+-ATPase from dog cardiac and rabbit skeletal muscle. J Biol Chem. 1983 Apr 25;258(8):5079–5083. [PubMed]
  • Ray KP, England PJ. Phosphorylation of the inhibitory subunit of troponin and its effect on the calcium dependence of cardiac myofibril adenosine triphosphatase. FEBS Lett. 1976 Nov;70(1):11–16. [PubMed]
  • Resink TJ, Gevers W. Dephosphorylation of myofibrillar proteins in actomyosin preparations and in isolated perfused rat hearts after beta-agonist withdrawal. J Mol Cell Cardiol. 1982 Jun;14(6):329–337. [PubMed]
  • Robertson SP, Johnson JD, Holroyde MJ, Kranias EG, Potter JD, Solaro RJ. The effect of troponin I phosphorylation on the Ca2+-binding properties of the Ca2+-regulatory site of bovine cardiac troponin. J Biol Chem. 1982 Jan 10;257(1):260–263. [PubMed]
  • Solaro RJ, Pang DC, Briggs FN. The purification of cardiac myofibrils with Triton X-100. Biochim Biophys Acta. 1971 Aug 6;245(1):259–262. [PubMed]
  • Solaro RJ, Moir AJ, Perry SV. Phosphorylation of troponin I and the inotropic effect of adrenaline in the perfused rabbit heart. Nature. 1976 Aug 12;262(5569):615–617. [PubMed]
  • Starr R, Offer G. Polypeptide chains of intermediate molecular weight in myosin preparations. FEBS Lett. 1971 Jun 2;15(1):40–44. [PubMed]
  • Stull JT, Buss JE. Phosphorylation of cardiac troponin by cyclic adenosine 3':5'-monophosphate-dependent protein kinase. J Biol Chem. 1977 Feb 10;252(3):851–857. [PubMed]
  • Tada M, Inui M. Regulation of calcium transport by the ATPase-phospholamban system. J Mol Cell Cardiol. 1983 Sep;15(9):565–575. [PubMed]
  • Tada M, Yamada M, Ohmori F, Kuzuya T, Inui M, Abe H. Transient state kinetic studies of Ca2+-dependent ATPase and calcium transport by cardiac sarcoplasmic reticulum. Effect of cyclic AMP-dependent protein kinase-catalyzed phosphorylation of phospholamban. J Biol Chem. 1980 Mar 10;255(5):1985–1992. [PubMed]

Articles from Biochemical Journal are provided here courtesy of The Biochemical Society

Formats:

Cited by other articles in PMC

See all...

Links

  • Compound
    Compound
    PubChem Compound links
  • MedGen
    MedGen
    Related information in MedGen
  • PubMed
    PubMed
    PubMed citations for these articles
  • Substance
    Substance
    PubChem Substance links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...