Dissecting ICRAC, a store-operated calcium current.

Area of Science:

• Cellular Biology
• Molecular Biology
• Biochemistry

Background:

• Intracellular calcium (Ca2+) signaling demands strict regulation of cytoplasmic Ca2+ levels.
• Store-operated calcium entry (SOCE) is a critical process where intracellular Ca2+ stores regulate Ca2+ influx across the plasma membrane.
• The specific molecular players mediating SOCE, particularly the Ca2+ current I(CRAC), remained undefined for over a decade.

Purpose of the Study:

• To elucidate the molecular components responsible for the Ca2+ current I(CRAC).
• To understand the signaling pathway connecting endoplasmic reticulum (ER) Ca2+ stores to plasma membrane Ca2+ entry.
• To investigate the evolutionary conservation of this ER-to-plasma membrane signaling system.

Main Methods:

• Biochemical identification of proteins involved in I(CRAC).
• Characterization of the STIM1 and Orai1 proteins.
• Analysis of the ER-to-plasma membrane signaling pathway.

Main Results:

• The key proteins STIM1 and Orai1 were identified as essential for I(CRAC).
• These proteins form a critical link between ER Ca2+ stores and plasma membrane Ca2+ influx.
• The identified pathway is conserved across multicellular organisms, highlighting its fundamental importance.

Conclusions:

• STIM1 and Orai1 are fundamental components of the store-operated calcium entry (SOCE) pathway.
• This discovery provides crucial insights into the ancient ER-to-plasma membrane Ca2+ signaling mechanism.
• Understanding SOCE is vital for comprehending cellular Ca2+ homeostasis and signaling.