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Ca2+ uptake and IP3-induced Ca2+ release in permeabilized human lymphocytes
FEBS Letters
|October 5, 1987
Summary
Human lymphocytes store calcium (Ca2+) in the endoplasmic reticulum. This ATP-dependent calcium uptake is significant and can be released by inositol trisphosphate (IP3).
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Intracellular calcium (Ca2+) signaling is crucial for lymphocyte function.
- Understanding the mechanisms of Ca2+ storage and release in lymphocytes is essential.
Purpose of the Study:
- To investigate the characteristics of Ca2+ uptake and release in human lymphocytes.
- To identify the primary intracellular Ca2+ storage site within these cells.
Main Methods:
- Utilized saponin-permeabilized human lymphocytes.
- Measured 45Ca2+ uptake and release.
- Assessed the effects of ATP, vanadate, oligomycin, ruthenium red, and inositol trisphosphate (IP3).
Main Results:
- Observed a significant ATP-dependent Ca2+ uptake into a non-mitochondrial, intracellular store, approximately 100 times greater than ATP-independent uptake.
- Ca2+ uptake was inhibited by vanadate but unaffected by oligomycin or ruthenium red.
- Inositol trisphosphate (IP3) induced dose-dependent 45Ca2+ release, with half-maximal release occurring at 0.25-0.5 microM IP3.
Conclusions:
- Human lymphocytes predominantly store 45Ca2+ within the endoplasmic reticulum.
- The identified Ca2+ store is likely an ATP-dependent pump sensitive to vanadate and responsive to IP3-mediated release.