Regulation of L-type calcium channel sparklet activity by c-Src and PKC-α

Jyoti Gulia, Manuel F Navedo, Peichun Gui, Jun Tzu Chao, Jose L. Mercado, Luis Fernando Santana, Michael J. Davis

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The activity of persistent Ca2+ sparklets, which are characterized by longer and more frequent channel open events than low-activity sparklets, contributes substantially to steady-state Ca2+ entry under physiological conditions. Here, we addressed two questions related to the regulation of Ca2+ sparklets by PKC-α and c-Src, both of which increase whole cell Cav1.2 current: 1) Does c-Src activation enhance persistent Ca2+ sparklet activity? 2) Does PKC-α activate c-Src to produce persistent Ca2+ sparklets? With the use of total internal reflection fluorescence microscopy, Ca2+ sparklets were recorded from voltage-clamped tsA-201 cells coexpressing wild-type (WT) or mutant Cav1.2c (the neuronal isoform of Cav1.2) constructs ± active or inactive PKC-α/c-Src. Cells expressing Cav1.2c exhibited both low-activity and persistent Ca2+ sparklets. Persistent Ca2+ sparklet activity was significantly reduced by acute application of the c-Src inhibitor PP2 or coexpression of kinase-dead c-Src. Cav1.2c constructs mutated at one of two COOH-terminal residues (Y2122F and Y2139F) were used to test the effect of blocking putative phosphorylation sites for c-Src. Expression of Y2122F but not Y2139F Cav1.2c abrogated the potentiating effect of c-Src on Ca2+ sparklet activity. We could not detect a significant change in persistent Ca2+ sparklet activity or density in cells coexpressing Cav1.2c + PKC-α, regardless of whether WT or Y2122F Cav1.2c was used, or after PP2 application, suggesting that PKC-α does not act upstream of c-Src to produce persistent Ca2+ sparklets. However, our results indicate that persistent Ca2+ sparklet activity is promoted by the action of c-Src on residue Y2122 of the Cav1.2c COOH terminus.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Issue number5
StatePublished - Sep 1 2013


  • Calcium entry
  • L-type calcium channel
  • Patch clamp
  • PKC
  • TIRF microscopy

ASJC Scopus subject areas

  • Cell Biology
  • Physiology


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