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KMID : 0360419940300010117
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Korean Journal of Pharmacology
1994 Volume.30 No. 1 p.117 ~ p.124
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Effect of a Phospholamban Peptide on the Skeletal Sarcoplasmic Reticulum Transport
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Kim Hea-Won
Lee Hee-Ran
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Abstract
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Phospholamban is the regulator of in cardiac sarcoplasmic reticulum(SR). The mechanism of regulation appears to involve inhibition by dephosphorylated phospholamban. Phosphorylation of phospholamban relieves this inhibition. Recently, there has been a report that the cytoplasmic domain (amino acids 1-25) of phospholamban is insufficient to inhibit the pump. To explore the domains of phospholamban responsible for inhibitory activity, we examined the effect of a synthetic phospholamban peptide consisting of amino acid residues 1-25 on uptake by reconstituted skeletal SR . The of skeletal SR was purified and reconstituted in proteoliposomes containing phosphatidylcholine (PC) or phosphatidylcholine: phosphatidylserine (PC:PS). Inclusion of a phospholamban peptide in PC proteoliposomes was associated with significant inhibition of the initial rates of uptake at pCa 6.0, and phosphorylation of this peptide by the catalytic subunit of cAMP-dependent protein kinase reversed the inhibitory effect on the pump. Similar effects of phospholamban peptide were also observed using PC:PS proteoliposomes. Based on these results, we could conclude that the cytoplasmic domain of phospholamban, containing the phosphorylation sites, by itself is sufficient to inhibit the pump of SR.
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KEYWORD
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Phospholamban, Sarcoplasmic reticulum, Reconstitution, Muscle
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