Nucleotide specificity of cardiac sarcoplasmic reticulum. GTP-induced calcium accumulation and GTPase activity - PubMed (original) (raw)
. 1985 Aug 15;260(17):9618-23.
- PMID: 2991255
Free article
Nucleotide specificity of cardiac sarcoplasmic reticulum. GTP-induced calcium accumulation and GTPase activity
C A Tate et al. J Biol Chem. 1985.
Free article
Abstract
We previously demonstrated that the hydrolysis of GTP by canine cardiac sarcoplasmic reticulum is not sensitive to calcium and does not support the translocation of calcium and oxalate into the vesicular space. In response to GTP, however, calcium is accumulated into a compartment which is sensitive to pH and ionophore. In the present paper, we further explored the relationship between GTP hydrolysis and GTP-induced calcium accumulation. Both ATP- and GTP-induced calcium accumulation were prevented by the sulfhydryl reagent, N-ethylmaleimide (NEM; I50 = 0.2 mM). In contrast, the sensitivity of NTP hydrolysis to NEM differed markedly; GTPase activity was not affected by NEM, whereas ATPase activity was markedly inhibited. Conversely, although the GTPase was noncompetitively inhibited by the ATP analogue, adenylyl imidodiphosphate (Ki = 8 microM), and was competitively inhibited by the GTP analogue, guanylyl imidodiphosphate (Ki = 60 microM), GTP-induced calcium accumulation was not affected by the NTP analogues at any concentration. Therefore, the GTP-dependent accumulation of calcium into the pH- and ionophore-sensitive compartment of cardiac SR may not require GTP hydrolysis but may be dependent on GTP binding. The previously reported noncompetitive inhibition of the GTPase by ATP was also observed when the calcium-dependent hydrolysis of ATP was prevented by NEM (Ki = 1.2 microM). Along with the noncompetitive inhibition of the GTPase by adenylyl imidodiphosphate, the inhibition of the GTP by ATP in the presence of NEM suggests that ATP binding may be involved in the observed inhibition. The Ki for the noncompetitive inhibition of GTPase activity is compatible with ATP binding to the high affinity catalytic site of the ATPase. Thus, although GTP-induced calcium accumulation differs somewhat from ATP-dependent calcium translocation, the similarities between the two processes (i.e. similar time courses and sensitivity to pH, ionophore, and sulfhydryl modification) suggest that they may be related in some manner.
Similar articles
- Nucleotide specificity of canine cardiac sarcoplasmic reticulum. Differential alteration of enzyme properties by detergent treatment.
Tate CA, Bick RJ, Blaylock SL, Youker KA, Scherer NM, Entman ML. Tate CA, et al. J Biol Chem. 1989 May 15;264(14):7809-13. J Biol Chem. 1989. PMID: 2524475
Cited by
- Cytosolic Ca²⁺ buffering determines the intra-SR Ca²⁺ concentration at which cardiac Ca²⁺ sparks terminate.
Bovo E, Mazurek SR, Fill M, Zima AV. Bovo E, et al. Cell Calcium. 2015 Sep;58(3):246-53. doi: 10.1016/j.ceca.2015.06.002. Epub 2015 Jun 10. Cell Calcium. 2015. PMID: 26095947 Free PMC article. - Flux regulation of cardiac ryanodine receptor channels.
Liu Y, Porta M, Qin J, Ramos J, Nani A, Shannon TR, Fill M. Liu Y, et al. J Gen Physiol. 2010 Jan;135(1):15-27. doi: 10.1085/jgp.200910273. Epub 2009 Dec 14. J Gen Physiol. 2010. PMID: 20008518 Free PMC article. - Tricyclic antidepressant amitriptyline alters sarcoplasmic reticulum calcium handling in ventricular myocytes.
Zima AV, Qin J, Fill M, Blatter LA. Zima AV, et al. Am J Physiol Heart Circ Physiol. 2008 Nov;295(5):H2008-16. doi: 10.1152/ajpheart.00523.2008. Epub 2008 Sep 12. Am J Physiol Heart Circ Physiol. 2008. PMID: 18790837 Free PMC article. - Calcium regulation of single ryanodine receptor channel gating analyzed using HMM/MCMC statistical methods.
Rosales RA, Fill M, Escobar AL. Rosales RA, et al. J Gen Physiol. 2004 May;123(5):533-53. doi: 10.1085/jgp.200308868. J Gen Physiol. 2004. PMID: 15111644 Free PMC article. - Unitary Ca2+ current through mammalian cardiac and amphibian skeletal muscle ryanodine receptor Channels under near-physiological ionic conditions.
Kettlun C, González A, Ríos E, Fill M. Kettlun C, et al. J Gen Physiol. 2003 Oct;122(4):407-17. doi: 10.1085/jgp.200308843. Epub 2003 Sep 15. J Gen Physiol. 2003. PMID: 12975450 Free PMC article.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Research Materials