store-operated calcium channel activity

Definition

Target type: molecularfunction

A ligand-gated ion channel activity which transports calcium in response to emptying of intracellular calcium stores. [GOC:dph, GOC:tb, PMID:15788710]

Store-operated calcium channels (SOCs) are a type of calcium channel that are activated by the depletion of calcium from intracellular stores. This depletion triggers the opening of the channel, allowing calcium ions to flow into the cell from the extracellular space. SOCs play a critical role in a wide range of cellular processes, including:

1. **Cell signaling:** Calcium is a ubiquitous second messenger that regulates many cellular functions, including gene expression, enzyme activity, and cell growth. SOCs are key players in calcium signaling pathways, as they provide a direct link between the depletion of intracellular calcium stores and the influx of extracellular calcium.

2. **Muscle contraction:** In muscle cells, calcium influx through SOCs is essential for muscle contraction. Depletion of calcium from the sarcoplasmic reticulum (SR), the intracellular calcium store in muscle cells, triggers the opening of SOCs, leading to calcium influx and subsequent muscle contraction.

3. **Exocytosis:** The process of exocytosis, in which cellular vesicles fuse with the plasma membrane and release their contents into the extracellular space, is also regulated by calcium. SOCs contribute to calcium-dependent exocytosis by providing the calcium influx necessary for vesicle fusion.

4. **Immune cell activation:** In immune cells, SOCs play a key role in the activation of immune responses. Calcium influx through SOCs activates signaling pathways that lead to the production of inflammatory cytokines and the activation of immune cells.

5. **Cell growth and differentiation:** SOCs are also involved in cell growth and differentiation. Calcium influx through SOCs can activate signaling pathways that promote cell proliferation and differentiation.

The molecular mechanism of SOC activation involves a complex interplay between several proteins, including stromal interaction molecule 1 (STIM1), Orai1, and TRPC1.

1. **STIM1:** STIM1 is a calcium sensor protein that resides in the ER membrane. When calcium levels in the ER decrease, STIM1 undergoes conformational changes that cause it to cluster at ER-plasma membrane junctions.

2. **Orai1:** Orai1 is a transmembrane protein that forms the pore of the SOC. STIM1 clusters bind to and activate Orai1, leading to the opening of the calcium channel.

3. **TRPC1:** TRPC1 is another calcium channel that can be activated by STIM1. However, the exact mechanism of TRPC1 activation and its role in SOCs are still being investigated.

In summary, SOCs are essential calcium channels that are activated by the depletion of intracellular calcium stores. They play a crucial role in a wide range of cellular processes, including cell signaling, muscle contraction, exocytosis, immune cell activation, and cell growth and differentiation. The molecular mechanism of SOC activation involves a complex interplay between several proteins, including STIM1, Orai1, and TRPC1.'
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Proteins (9)

Compounds (22)