ORAI2

ORAI2 is a protein that in humans is encoded by the ORAI2 gene. It is a member of the ORAI family of proteins, which play a critical role in the regulation of cellular calcium signaling. Calcium signaling is essential for a variety of cellular processes, including muscle contraction, neurotransmitter release, and gene expression. The ORAI proteins are best known for their function as components of the calcium release-activated calcium (CRAC) channel, which is a vital element of the store-operated calcium entry (SOCE) pathway.

Function

The ORAI2 protein functions as a subunit of the CRAC channel. It is involved in the SOCE pathway, where it helps mediate the influx of calcium ions into the cell. This influx is triggered in response to the depletion of calcium from the endoplasmic reticulum (ER). The ER serves as a major calcium store within the cell, and its depletion signals the need for external calcium to enter the cell to replenish these stores. The ORAI2-containing CRAC channels are located on the plasma membrane and open in response to the interaction with the stromal interaction molecule (STIM), a sensor of calcium levels within the ER. This interaction between STIM and ORAI proteins facilitates the entry of calcium into the cell.

Clinical Significance

Alterations in the function or expression of ORAI2 can have significant implications for human health. Given its role in calcium signaling, ORAI2 has been implicated in various pathological conditions. Abnormalities in calcium homeostasis are associated with a range of diseases, including immune disorders, muscular diseases, and neurodegenerative conditions. Research into the specific contributions of ORAI2 to these diseases is ongoing, with the potential for targeting the SOCE pathway in therapeutic interventions.

Genetic

The ORAI2 gene is located on chromosome 7 in humans. It shares a high degree of homology with other members of the ORAI family, particularly ORAI1, which is the best-characterized member of this family. Despite their similarities, each ORAI protein exhibits unique regulatory features and tissue distribution, suggesting that they may have distinct physiological roles.

See Also

• Calcium signaling
• Endoplasmic reticulum
• Stromal interaction molecule
• ORAI1
• Store-operated calcium entry