stretch-activated, monoatomic cation-selective, calcium channel activity

Definition

Target type: molecularfunction

Enables the transmembrane transfer of a calcium ion by a channel that opens in response to a mechanical stress in the form of stretching. [GOC:mtg_transport]

Stretch-activated, monoatomic cation-selective, calcium channels are integral membrane proteins that play a critical role in mechanotransduction, the process by which cells convert mechanical stimuli into biochemical signals. These channels are activated by mechanical forces, such as membrane tension or stretching, and they selectively allow the passage of monoatomic cations, primarily calcium ions (Ca2+), across the cell membrane. The molecular function of these channels can be broken down into the following key aspects:

1. **Mechanical Sensing:** The channels are equipped with specialized domains or regions that are sensitive to mechanical forces. These domains can be located within the transmembrane regions of the channel protein, or they can be linked to the cytoskeleton or extracellular matrix. Upon sensing a stretch or deformation of the cell membrane, these domains undergo conformational changes that ultimately lead to channel opening.

2. **Gate Opening:** The mechanical force-induced conformational changes in the channel protein alter the structure of the ion permeation pathway, causing it to open. This opening allows ions to flow across the membrane, down their electrochemical gradient.

3. **Ion Selectivity:** Stretch-activated calcium channels exhibit a high degree of selectivity for monoatomic cations, particularly Ca2+. This selectivity is achieved through the unique arrangement of amino acid residues within the channel pore. These residues create a favorable environment for the passage of small, positively charged ions, while excluding larger molecules or negatively charged ions.

4. **Calcium Influx:** The opening of stretch-activated calcium channels results in an influx of Ca2+ ions into the cell. This calcium influx plays a critical role in various cellular processes, including:
* **Muscle contraction:** Calcium influx triggers the release of acetylcholine from nerve terminals, leading to muscle fiber contraction.
* **Vascular tone regulation:** Calcium influx in smooth muscle cells regulates the diameter of blood vessels, influencing blood flow and blood pressure.
* **Sensory transduction:** Calcium influx contributes to the transduction of sensory signals, such as touch, pressure, and pain.
* **Cell signaling:** Calcium influx acts as a second messenger, triggering downstream signaling cascades involved in cell growth, differentiation, and apoptosis.

5. **Channel Closure:** Following the application of mechanical force, the channel eventually closes, preventing further calcium influx. The closure mechanism can involve the reversal of conformational changes in the channel protein or the interaction with regulatory proteins.

In summary, stretch-activated, monoatomic cation-selective, calcium channels are highly specialized proteins that act as mechanical sensors and calcium entry pathways, playing critical roles in various physiological processes. Their molecular function is characterized by their ability to respond to mechanical stimuli, open and close in a regulated manner, selectively allow the passage of calcium ions, and contribute to calcium-mediated cellular responses.'
"

Proteins (1)

Compounds (9)