Which one of the following acts to increase the release of Ca2 from endoplasmic reticulum?
**Core Concept**
The process of increasing the release of Ca2 from the endoplasmic reticulum is crucial for various cellular functions, including muscle contraction and neurotransmitter release. This process is mediated by specific receptors and channels that regulate the flow of calcium ions.
**Why the Correct Answer is Right**
The correct answer, Inositol trisphosphate (IP3), acts by binding to its receptor on the endoplasmic reticulum, leading to the opening of IP3 receptors and a subsequent release of Ca2 into the cytosol. This process is a key step in the intracellular signaling pathway initiated by the binding of agonists to Gq-coupled receptors. The increase in cytosolic Ca2 then triggers various downstream effects, including the activation of protein kinase C and the regulation of gene expression.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is unclear and does not accurately represent a known substance involved in the regulation of Ca2 release from the endoplasmic reticulum.
* **Option B:** This option is also unclear and does not accurately represent a known substance involved in the regulation of Ca2 release from the endoplasmic reticulum.
* **Option D:** This option is not relevant to the regulation of Ca2 release from the endoplasmic reticulum.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the IP3 receptor is a critical component of the intracellular signaling pathway initiated by Gq-coupled receptors, and its dysregulation has been implicated in various diseases, including cancer and cardiovascular disease.
**Correct Answer:** C. IP3 (Inositol trisphosphate)