inositol 1,4,5-trisphosphate-gated calcium channel activity

Definition

Target type: molecularfunction

Enables the transmembrane transfer of a calcium ion by a channel that opens when inositol 1,4,5-trisphosphate (IP3) has been bound by the channel complex or one of its constituent parts. [GOC:mah, GOC:signaling, PMID:28416699, PMID:8660280, Wikipedia:Inositol_trisphosphate_receptor]

Inositol 1,4,5-trisphosphate-gated calcium channel activity is a crucial molecular function involved in calcium signaling within cells. It refers to the ability of a specific type of calcium channel, known as the inositol 1,4,5-trisphosphate receptor (IP3R), to open and allow the influx of calcium ions (Ca2+) into the cytoplasm.

The IP3R is a transmembrane protein located on the endoplasmic reticulum (ER), a cellular organelle serving as a calcium store. The channel is activated by the binding of inositol 1,4,5-trisphosphate (IP3), a second messenger molecule generated in response to various extracellular stimuli like hormones and neurotransmitters. Upon IP3 binding, the IP3R undergoes a conformational change, opening its pore and facilitating the release of Ca2+ from the ER lumen into the cytosol.

This calcium influx plays a fundamental role in a wide range of cellular processes, including:

* **Muscle contraction:** Calcium release from the ER triggers muscle contraction by interacting with troponin, a regulatory protein involved in muscle fiber activation.
* **Neurotransmitter release:** In neurons, calcium influx through IP3Rs triggers the release of neurotransmitters from synaptic vesicles, enabling communication between nerve cells.
* **Cell growth and differentiation:** Calcium signaling via IP3Rs is crucial for cell cycle regulation, proliferation, and differentiation in various cell types.
* **Gene expression:** Calcium influx can modulate gene expression by activating transcription factors and other regulatory proteins.
* **Apoptosis (programmed cell death):** Calcium release through IP3Rs is involved in the apoptotic pathway, contributing to the controlled dismantling of cells.

The precise mechanisms by which IP3Rs regulate these processes are complex and involve interactions with various intracellular signaling molecules. Dysregulation of IP3R activity can lead to pathological conditions, including neurodegenerative disorders, cardiovascular diseases, and cancer.

In summary, inositol 1,4,5-trisphosphate-gated calcium channel activity represents a critical molecular function in calcium signaling, enabling the release of calcium from intracellular stores and orchestrating a diverse array of cellular processes.'
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Proteins (3)

Compounds (1)