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Isolation of Human Myoblasts, Assessment of Myogenic Differentiation, and Store-operated Calcium Entry Measurement
Published on: July 26, 2017
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Type 3 inositol 1,4,5-trisphosphate receptor and capacitative calcium entry
1Calcium Regulation Section, National Institute of Environmental Health Sciences-NIH, Research Triangle Park, North Carolina 27709, USA. Putney@niehs.nih.gov
Cell Calcium
|March 1, 1997
Summary
Capacitative calcium entry, crucial for cell signaling, may involve the inositol 1,4,5-trisphosphate (IP3) receptor type 3. This receptor, distinct from TRP channels, shows functional evidence for mediating calcium influx.
Area of Science:
- Cell Biology
- Molecular Physiology
- Ion Channel Function
Background:
- Depletion of intracellular calcium stores activates calcium influx via capacitative calcium entry.
- Transient Receptor Potential (TRP) channels are primary candidates for mediating this calcium influx.
- Emerging evidence suggests alternative mechanisms for capacitative calcium entry.
Purpose of the Study:
- To investigate the role of the type 3 inositol 1,4,5-trisphosphate (IP3) receptor in capacitative calcium entry.
- To compare the properties of IP3 receptor-mediated calcium entry with TRP channel function.
- To explore the evolutionary implications of different channel families mediating similar cellular functions.
Main Methods:
- Analysis of Ca2+ currents and channel properties in cell types expressing the type 3 IP3 receptor.
- Investigation of direct IP3 activation of plasma membrane channels.
- Functional expression of the type 3 IP3 receptor in Xenopus oocytes to assess its role in Ca2+ entry.
Main Results:
- Calcium currents activated by store depletion in some cells resemble those of the type 3 IP3 receptor.
- Inositol 1,4,5-trisphosphate directly activates plasma membrane channels, including those activated by store depletion.
- Expression of the type 3 IP3 receptor in Xenopus oocytes facilitates calcium entry across the plasma membrane.
Conclusions:
- The type 3 IP3 receptor represents a functional capacitative calcium entry channel in certain cell types.
- TRP channels may mediate capacitative calcium entry in other cell types, suggesting distinct molecular mechanisms.
- The lack of homology between IP3 and TRP families points to convergent evolution of calcium influx pathways.
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