Regulatory role of phospholamban in the efficiency of cardiac sarcoplasmic reticulum Ca2+ transport

K. Frank, C. Tilgmann, T. R. Shannon, Donald M Bers, E. G. Kranias

Research output: Contribution to journalArticle

30 Citations (Scopus)

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 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.

Original languageEnglish (US)
Pages (from-to)14176-14182
Number of pages7
JournalBiochemistry
Volume39
Issue number46
DOIs
StatePublished - Nov 21 2000
Externally publishedYes

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Sarcoplasmic Reticulum
Phosphorylation
Adenosine Triphosphate
Cyclic AMP-Dependent Protein Kinase Catalytic Subunits
Calcium-Transporting ATPases
phospholamban
Ablation
Muscle Cells
Muscle
Hydrolysis
Myocardium

ASJC Scopus subject areas

  • Biochemistry

Cite this

Regulatory role of phospholamban in the efficiency of cardiac sarcoplasmic reticulum Ca2+ transport. / Frank, K.; Tilgmann, C.; Shannon, T. R.; Bers, Donald M; Kranias, E. G.

In: Biochemistry, Vol. 39, No. 46, 21.11.2000, p. 14176-14182.

Research output: Contribution to journalArticle

Frank, K. ; Tilgmann, C. ; Shannon, T. R. ; Bers, Donald M ; Kranias, E. G. / Regulatory role of phospholamban in the efficiency of cardiac sarcoplasmic reticulum Ca2+ transport. In: Biochemistry. 2000 ; Vol. 39, No. 46. pp. 14176-14182.
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