Insulin acts through which channel/transporter-
**Core Concept**
Insulin is a hormone that regulates glucose metabolism by facilitating glucose uptake in cells. It binds to specific receptors on the surface of target cells, triggering a cascade of intracellular signaling pathways. The primary mechanism of insulin action involves the regulation of glucose transport across the cell membrane.
**Why the Correct Answer is Right**
Insulin binds to its receptor, which activates the tyrosine kinase domain. This activation leads to the autophosphorylation of the receptor and the recruitment of insulin receptor substrate (IRS) proteins. The IRS proteins interact with phosphatidylinositol 3-kinase (PI3K), which in turn activates phosphodiesterase (PDE) and inhibits protein kinase B (PKB), also known as Akt. The inhibition of PKB leads to the translocation of GLUT4 glucose transporters to the plasma membrane, allowing glucose to enter the cell.
**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because insulin does not act through voltage-gated potassium channels.
**Option B:** is incorrect because insulin does not directly activate the sodium-potassium pump.
**Option C:** is incorrect because insulin does not act through the cystic fibrosis transmembrane conductance regulator (CFTR) channel.
**Option D:** is incorrect because insulin does not directly interact with the sodium-calcium exchanger.
**Clinical Pearl / High-Yield Fact**
The translocation of GLUT4 glucose transporters to the plasma membrane is a key regulatory mechanism of glucose uptake in response to insulin. This process is impaired in insulin resistance and type 2 diabetes.
**Correct Answer:** GLUT4