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Updated: Oct 7, 2025

Single-Cell Calcium Imaging for Studying the Activation of Calcium Ion Channels
Published on: December 13, 2024
Annexin A3: a newly identified player in store‑operated calcium entry
Agnieszka Dyrda1, Jacek Kuznicki1, Lukasz Majewski2
1Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland.
Abstract:
Store‑operated calcium entry (SOCE) is important for refilling endoplasmic reticulum (ER) Ca2+ stores and Ca2+ signaling. Extracellular Ca2+ is conducted by highly Ca2+‑selective Orai channels that are activated by stromal interaction molecule proteins (STIMs), which are sensitive ER Ca2+ sensors. We found an approximately five‑fold increase in annexin A3a (anxa3a) expression levels in stim2b knockout zebrafish. The present study investigated whether annexin A3 protein is involved in SOCE. We used Ca2+ imaging and electrophysiological recordings to determine the effect of annexin A2, A3, and A6 overexpression on SOCE and Orai-dependent Ca2+ currents (ICRAC) in cultured cells. Annexin A3 increased SOCE amplitude and potentiated Ca2+ ICRAC currents. These results suggest that annexin A3 is a positive modulator of SOCE.
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