Flash photolysis of caged inositol 1,4,5-trisphosphate activates plasma membrane calcium current in human T cells

T. V. McDonald, B. A. Premack, P. Gardner

Research output: Contribution to journalArticle

97 Scopus citations

Abstract

Sustained elevation of intracellular Ca2+ by cell surface receptors is often dependent on influx of Ca2+ across the plasma membrane through routes not involving voltage-gated Ca2+ channels. We demonstrate that intracellular release of inositol 1,4,5-trisphosphate (InsP3), either from stimulation of transfected human muscarinic receptors or from photolytic release of caged InsP3, activates whole cell Ca2+ current in the Jurkat T cell line. Whole cell voltage clamp recordings indicate that the current is carried by a Ca2+-selective channel that resembles T-type voltage-gated Ca2+ channels in relative conductance of different cation species. Elevation of internal Ca2+ inactivates the channel, whereas internal perfusion with inositol 1,3,4,5-tetrakisphosphate (InsP4) does not affect it. Photolytic release of caged 1-(α-glycerophosphoryl)-inositol 4,5- bisphosphate, an analog of InsP3 which activates InsP3 receptors but is not readily metabolized to InsP4, also activates the current. We conclude that generation of InsP3 is sufficient to activate Ca2+-selective channels in the plasma membrane of T cells. InsP3 may have its effect indirectly through depletion of Ca2+ stores, or directly with a plasma membrane-associated InsP3 receptor.

Original languageEnglish (US)
Pages (from-to)3889-3896
Number of pages8
JournalJournal of Biological Chemistry
Volume268
Issue number6
StatePublished - 1993

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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