High-level coexpression of the canine cardiac calcium pump and phospholamban in Sf21 insect cells

Joseph M. Autry, Larry Jones

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Phospholamban is a pentameric transmembrane phosphoprotein that regulates the activity of the Ca2+-transporting ATPase (SERCA2a) in cardiac sarcoplasmic reticulum. To better understand the structure and function of phospholamban and its mode of regulation of the ATPase, phospholamban and SERCA2a were coexpressed at high levels in Sf21 insect cells using the baculovirus expression system, SERCA2a was expressed as a functionally active Ca2+ pump, accounting for ≥ 20% of the total protein in Sf21 cell microsomes. Wild-type phospholamban, as well as phospholamban with different point mutations in the transmembrane region, inhibited both Ca2+ transport and ATP hydrolysis by the recombinant Ca2+ pump. The inhibition of SERCA2a activity,vas reversed by an anti-phospholamban monoclonal antibody. The phospholamban molecules studied decreased the apparent Ca2+ affinity of the Ca2+ pump, but had no effect on enzyme velocity measured at saturating Ca2+ concentration. Monomeric phospholamban produced by mutations in the leucine/isoleucine zipper domain decreased the apparent Ca2+ affinity the most, giving stronger inhibition of the Ca2+ pump than even wild-type phospholamban. Thus, the baculovirus cell expression system is ideally suited for examining functional interactions between phospholamban and SERCA2a. The results obtained suggest that the phospholamban monomer may be the active species inhibiting the Ca2+ pump in the cardiac sarcoplasmic reticulum membrane.

Original languageEnglish
Pages (from-to)92-102
Number of pages11
JournalAnnals of the New York Academy of Sciences
Volume853
StatePublished - 1998

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Sf9 Cells
Insects
Canidae
Pumps
Calcium
Baculoviridae
Sarcoplasmic Reticulum
Adenosine Triphosphatases
phospholamban
Cells
Insect
Leucine Zippers
Calcium-Transporting ATPases
Isoleucine
Fasteners
Phosphoproteins
Affinity
Mutation
Microsomes
Point Mutation

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

Cite this

High-level coexpression of the canine cardiac calcium pump and phospholamban in Sf21 insect cells. / Autry, Joseph M.; Jones, Larry.

In: Annals of the New York Academy of Sciences, Vol. 853, 1998, p. 92-102.

Research output: Contribution to journalArticle

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