cAMP-dependent phosphorylation sites and macroscopic activity of recombinant cardiac L-type calcium channels

Gabor Mikala, Udo Klöckner, Maria Varadi, Jörg Eisfeld, Arnold Schwartz, Gyula Varadi

Research output: Contribution to journalArticle

23 Citations (Scopus)


The involvement of cAMP-dependent phosphorylation sites in establishing the basal activity of cardiac L-type Ca2+ channels was studied in HEK 293 cells transiently cotransfected with mutants of the human cardiac α1 and accessory subunits. Systematic individual or combined elimination of high consensus protein kinase A (PKA) sites, by serine to alanine substitutions at the amino and carboxyl termini of the α1 subunit, resulted in Ca2+ channel currents indistinguishable from those of wild type channels. Dihydropyridine (DHP)-binding characteristics were also unaltered. To explore the possible involvement of nonconsensus sites, deletion mutants were used. Carboxyl-terminal truncations of the α1 subunit distal to residue 1597 resulted in increased channel expression and current amplitudes. Modulation of PKA activity in cells transfected with the wild type channel or any of the mutants did not alter Ca2+ channel functions suggesting that cardiac Ca2+ channels expressed in these cells behave, in terms of lack of PKA control, like Ca2+ channels of smooth muscle cells.

Original languageEnglish
Pages (from-to)95-109
Number of pages15
JournalMolecular and Cellular Biochemistry
Issue number1-2
Publication statusPublished - Sep 14 1998


  • Calcium channel
  • Dihydropyridine
  • Electrophysiology
  • Mutagenesis
  • Phosphorylation

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

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