Role of protein kinase C in phospholemman mediated regulation of α 2β 1 isozyme of Na +/K +-ATPase in caveolae of pulmonary artery smooth muscle cells

Kuntal Dey, Soumitra Roy, Biswarup Ghosh, Sajal Chakraborti

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

We have recently reported that α 2β 1 and α 1β 1 isozymes of Na +/K +-ATPase (NKA) are localized in the caveolae whereas only the α 1β 1 isozyme of NKA is localized in the non-caveolae fraction of pulmonary artery smooth muscle cell membrane. It is well known that different isoforms of NKA are regulated differentially by PKA and PKC, but the mechanism is not known in the caveolae of pulmonary artery smooth muscle cells. Herein, we examined whether this regulation occurs through phospholemman (PLM) in the caveolae. Our results suggest that PKC mediated phosphorylation of PLM occurs only when it is associated with the α 2 isoform of NKA, whereas phosphorylation of PLM by PKA occurs when it is associated with the α 1 isoform of NKA. To investigate the mechanism of regulation of α 2 isoform of NKA by PKC-mediated phosphorylation of PLM, we have purified PLM from the caveolae and reconstituted into the liposomes. Our result revealed that (i) in the reconstituted liposomes phosphorylated PLM (PKC mediated) stimulate NKA activity, which appears to be due to an increase in the turnover number of the enzyme; (ii) phosphorylated PLM did not change the affinity of the pump for Na +; and (iii) even after phosphorylation by PKC, PLM still remains associated with the α 2 isoform of NKA.

Original languageEnglish
Pages (from-to)991-1000
Number of pages10
JournalBiochimie
Volume94
Issue number4
DOIs
StatePublished - 1 Apr 2012
Externally publishedYes

Keywords

  • Caveolae
  • Na /K -ATPase isozyme
  • PKA
  • PKC
  • PLM

ASJC Scopus subject areas

  • Biochemistry

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