Regulatory role of phospholamban in the efficiency of cardiac sarcoplasmic reticulum Ca2+ transport
(2000) In Biochemistry 39(46). p.14176-14182- Abstract
Phospholamban is an inhibitor of the sarcoplasmic reticulum Ca2+ transport apparent affinity for Ca2+ in cardiac muscle. This inhibitory effect of phospholamban can be relieved through its phosphorylation or ablation. To better characterize the regulatory mechanism of phospholamban, we examined the initial rates of Ca2+-uptake and Ca2+-ATPase activity under identical conditions, using sarcoplasmic reticulum-enriched preparations from phospholamban-deficient and wild-type hearts. The apparent coupling ratio, calculated by dividing the initial rates of Ca2+ transport by ATP hydrolysis, appeared to increase with increasing [Ca2+] in wild-type hearts. However, in the... (More)
Phospholamban is an inhibitor of the sarcoplasmic reticulum Ca2+ transport apparent affinity for Ca2+ in cardiac muscle. This inhibitory effect of phospholamban can be relieved through its phosphorylation or ablation. To better characterize the regulatory mechanism of phospholamban, we examined the initial rates of Ca2+-uptake and Ca2+-ATPase activity under identical conditions, using sarcoplasmic reticulum-enriched preparations from phospholamban-deficient and wild-type hearts. The apparent coupling ratio, calculated by dividing the initial rates of Ca2+ transport by ATP hydrolysis, appeared to increase with increasing [Ca2+] in wild-type hearts. However, in the phospholamban-deficient hearts, this ratio was constant, and it was similar to the value obtained at high [Ca2+] in wild-type hearts. Phosphorylation of phospholamban by the catalytic subunit of protein kinase A in wild-type sarcoplasmic reticulum also resulted in a constant value of the apparent ratio of Ca2+ transported per ATP hydrolyzed, which was similar to that present in phospholamban-deficient hearts. Thus, the inhibitory effects of dephosphorylated phospholamban involve decreases in the apparent affinity of sarcoplasmic reticulum Ca2+ transport for Ca2+ and the efficiency of this transport system at low [Ca2+], both leading to prolonged relaxation in myocytes.
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- author
- Frank, K. ; Tilgmann, C. LU ; Shannon, T. R. ; Bers, D. M. and Kranias, E. G.
- publishing date
- 2000-11-21
- type
- Contribution to journal
- publication status
- published
- in
- Biochemistry
- volume
- 39
- issue
- 46
- pages
- 7 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:11087366
- scopus:0034700256
- ISSN
- 0006-2960
- DOI
- 10.1021/bi001049k
- language
- English
- LU publication?
- no
- id
- b1d4e674-9b77-4425-a496-40193a14b5f7
- date added to LUP
- 2016-04-11 13:16:28
- date last changed
- 2024-01-04 01:09:25
@article{b1d4e674-9b77-4425-a496-40193a14b5f7, abstract = {{<p>Phospholamban is an inhibitor of the sarcoplasmic reticulum Ca<sup>2+</sup> transport apparent affinity for Ca<sup>2+</sup> in cardiac muscle. This inhibitory effect of phospholamban can be relieved through its phosphorylation or ablation. To better characterize the regulatory mechanism of phospholamban, we examined the initial rates of Ca<sup>2+</sup>-uptake and Ca<sup>2+</sup>-ATPase activity under identical conditions, using sarcoplasmic reticulum-enriched preparations from phospholamban-deficient and wild-type hearts. The apparent coupling ratio, calculated by dividing the initial rates of Ca<sup>2+</sup> transport by ATP hydrolysis, appeared to increase with increasing [Ca<sup>2+</sup>] in wild-type hearts. However, in the phospholamban-deficient hearts, this ratio was constant, and it was similar to the value obtained at high [Ca<sup>2+</sup>] in wild-type hearts. Phosphorylation of phospholamban by the catalytic subunit of protein kinase A in wild-type sarcoplasmic reticulum also resulted in a constant value of the apparent ratio of Ca<sup>2+</sup> transported per ATP hydrolyzed, which was similar to that present in phospholamban-deficient hearts. Thus, the inhibitory effects of dephosphorylated phospholamban involve decreases in the apparent affinity of sarcoplasmic reticulum Ca<sup>2+</sup> transport for Ca<sup>2+</sup> and the efficiency of this transport system at low [Ca<sup>2+</sup>], both leading to prolonged relaxation in myocytes.</p>}}, author = {{Frank, K. and Tilgmann, C. and Shannon, T. R. and Bers, D. M. and Kranias, E. G.}}, issn = {{0006-2960}}, language = {{eng}}, month = {{11}}, number = {{46}}, pages = {{14176--14182}}, publisher = {{The American Chemical Society (ACS)}}, series = {{Biochemistry}}, title = {{Regulatory role of phospholamban in the efficiency of cardiac sarcoplasmic reticulum Ca2+ transport}}, url = {{http://dx.doi.org/10.1021/bi001049k}}, doi = {{10.1021/bi001049k}}, volume = {{39}}, year = {{2000}}, }