Inositol 1,4,5-triphosphate-triggered Ca2+ release from bovine adrenal medullary secretory vesicles

Seung Hyun Yoo, Joseph P. Albanesi

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

The effect of inositol 1,4,5-triphosphate (Ins(1,4,5)-P3) and calcium ionophore A23187 on Ca2+ release from bovine adrenal medullary secretory vesicles and microsomes was examined. Ins(1,4,5)P3 released 3.5 nmol of Ca2+/mg protein from secretory vesicles and 1.5 nmol of Ca2+/mg protein from microsomes as measured by a Ca2+-selective electrode. However, A23187 promoted Ca2+ uptake into vesicles while releasing Ca2+ from microsomes. Ins(1,4,5)P3-induced Ca2+ release from secretory vesicles was rapid, but the released Ca2+ was absorbed within 3 min during which the Ins(1,4,5)P3-releasable pools were refilled. The in situ calcium content of secretory vesicle measured by atomic absorption spectrometry was 112 ± 6.3 nmol/mg protein indicating the potential importance of secretory vesicles as an intracellular Ca2+ store. The high Ca2+-buffering capacity of secretory vesicles is presumed to be due to the high Ca2+-binding capacity of chromograninin A, the major intravesicular protein, which has calsequestrin-like properties.

Original languageEnglish (US)
Pages (from-to)13446-13448
Number of pages3
JournalJournal of Biological Chemistry
Volume265
Issue number23
StatePublished - Aug 31 1990

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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