The two high affinity calcium binding sites of the cardiac (Ca2+ + Mg2+)-ATPase have been identified with the use of Eu3+. Eu3+ competes for the two high affinity calcium sites on the enzyme. With the use of laser-pulsed fluorescent spectroscopy, the environment of the two sites appear to be heterogeneous and contain different numbers of H2O molecules coordinated to the ion. The ion appears to be occluded even further in the presence of ATP. Using non-radiative energy transfer studies, we were able to estimate the distance between the two Ca2+ sites to be between 9.4 to 10.2 A in the presence of ATP. Finally, from the assumption that the calcium site must contain four carboxylic side chains to provide the 6–8 ligands needed to coordinate calcium, and based on our recently published data, we predict the peptidic backbone of the two sites.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Ambudkar IS, Fanfarillo DT, Shamoo AE: Phospholamban involvement in the maintenance of basal calcium transport in cardiac sarcoplasmic reticulum. Membrane Biochemistry 6:327–346, 1986
Bidlack JM, Shamoo AE: Adenosine 3′,5′-monophosphate dependent phosphorylation of A6000 and 22000 dalton protein from cardiac sarcoplasmic reticulum. Biochim Biophys Acta 632:310–325, 1980
Bidlack JM, Ambudkar IS, Shamoo AE: Purification of phospholamban, a 22000 dalton protein from cardiac sarcoplasmic reticulum that is especially phosphorylated by cyclic AMP dependent protein kinase. J Biol Chem 257:4501–4506, 1982
Gangola P, Shamoo AE: Characterization of (Ca2+ + Mg2+)-ATPase of sarcoplasmic reticulum by laserexcited europium luminescence. Eur J Biochemistry 162:357–363, 1987
Herrmann TR, Jayaweera RA, Ambudkar IS, Shamoo AE: Characterization of calciphorin by laser-excited europium luminescence. Biochem Biophys Acta 774:11–18, 1984
Herrmann TR, Jayaweera AR, Shamoo AE: Interaction of europium (III) with phospholipid vesicles as monitored by laser-excited europium (III) luminescence. Biochemistry 25:5834–5838, 1986
Horrocks WDeW, Rhee M-J, Snyder AP, Sudnick DR: Laser induced metal ion luminescence: interlanthanide ion energy transfer distance measurements in the calcium-binding proteins, parvalbumin and hemoglobin. Metalloprotein models address a photophysical problem. J Am Chem Soc 102:3650–3652, 1980
Joshi NB, Shamoo AE: Binding of Eu3+ to cardiac sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase-laser excited Eu3+ spectroscopic studies. Biophys J 51:185–191, 1987
Matthews BW, Weaver LH, Kester WR: The conformation of thermolysin. J Biol Chem 249:8030–8044, 1974
Orlov SN, Sitozhevsky AV, Pokudin NI, Karagodina ZV, Rhyazhsky GG: Biological Membranes (USSR) 2:976–984, 1985
Rhee M-J, Sudnick DR, Arkle VK, Horrocks WDeW: Lanthanide ion luminescence probes. Characterization of metal ion binding sites and intermetal energy transfer distance measurements in calcium binding proteins. 1. parvalbumin. Biochemistry 20:3328–3334, 1981
Scott TL, Shamoo AE: Disruption of energy transduction in sarcoplasmic reticulum. J Membrane Biol 64:137–144, 1982
Scott TL: Sits of the (Ca2+ + Mg2+)-ATPase of sarcoplasmic reticulum. J Biol Chem 260:14421–14423, 1985
Scott TL, Shamoo AE: Distinction of the roles of the two high affinity calcium sites in the functional activities of the Ca2+ ATPase of sarcoplasmic reticulum. Eur J Biochem 143:427–436, 1984
Serpersu EH, Kirch U, Schoner W: Demonstration of a stable occluded form of Ca2+ by the use of the chromium complex of ATP in the Ca2+ ATPase of sarcoplasmic reticulum. Eur J Biochem 122:347–354, 1982
Shamoo AE: Overal regulations of calcium transport in muscle. In: Shamoo AE (ed) Regulation of calcium transport across muscle membranes. Current Topics in Membranes and Transport, Vol 25. Academic press, New York, NY, 1985, pp 1–7
Shamoo AE, Ambudkar IS: Regulations of calcium transport in cardiac cells. Can J Physiol Pharmacol 62:9–22, 1984
Shamoo AE, Ambudkar IS, Jacobson MS, Bidlack J: Regulation of calcium transport in cardiac sarcoplasmic reticulum. In: Shamoo AE (ed) Regulation of calcium transport across muscle membranes. Current Topics in Membranes and Transport, Vol 25. Academic Press, New York, NY, 1985, pp 131–145
Shamoo AE, Herrmann TR, Gangola P, Joshi JB: Biophysical aspects of Ca2+-transport sites in skeletal and cardiac sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase. In: Dhalla NS, Grant NP, Beamish RE (eds) Proceeding of the ‘Symposium on Heart Metabolism in Health and Disease’ July 8–11, 1986. Winnipeg, Canada. Martinus Nijhoff/Dr Junk Publishers, 1987, pp 221–241
Shamoo AE, Joshi NB: Regulation of the peptide region of the calcium and ATP sites of the calcium pump protein. In: Bronner F, Peterlik M (eds) Proceedings of the third international workshop on ‘Calcium and Phosphate Transport Across Biomembranes’ Vienna, Austria, March 1–4. Alan Liss Inc Publ, New York, NY, 1987
Sudnick DR: Laser-induced luminescence of lanthanide ions as a structural probe of coordination complexes and biological macromolecules. PhD Thesis, The Pennsylvania State University, University Park, PA, 1979, 110 pp
Synder AP, Sudnick DR, Arkel VR, Horrocks W DeW: Lanthanide ion luminescence probes. Characterization of metal ion binding sites and intermetal energy transfer distance measurements in calcium binding proteins. 2. Thermolysin. Biochemistry 20:3334–3339, 1981
Stryer L: Fluorescence energy transfer as a spectroscopic ruler. Annu Rev Biochem 47:819–846, 1978
Tada M, Yamada M, Kamada M, Inui M, Ohmoori F: Calcium transport by cardiac sarcoplasmic reticulum and phosphorylation of phospholamban. Mol Cell Biochem 46:73–95, 1982
Wang CLA, Tao T, Gergely J: The distance between the high affinity sites of troponin-C measured by interlanthanide ion energy transfer. J Biol Chem 257:8372–8375, 1982
Williams RJP: In: Wasserman et al (eds) Calcium Binding Proteins and Calcium Function. North-Holland, New York, 1977, 3–11
About this article
Cite this article
Shamoo, A.E., Joshi, N.B. & Lockwich, T. Regulation of cardiac sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase. Mol Cell Biochem 82, 45–49 (1988). https://doi.org/10.1007/BF00242514
- sarcoplasmic reticulum
- Ca2+-binding sites