Glucose transporter present in RBCs
**Core Concept**
Glucose transporters are a family of membrane proteins that facilitate the transport of glucose across cell membranes. In red blood cells (RBCs), glucose is essential for energy production, and the specific glucose transporter allows for the uptake of glucose from the bloodstream.
**Why the Correct Answer is Right**
The glucose transporter present in RBCs is GLUT1, which is a facilitative diffusion transporter that allows glucose to enter the cell down its concentration gradient. GLUT1 is a constitutively expressed transporter, meaning it is always present and active in RBCs, allowing for a constant supply of glucose for energy production. This is particularly important in RBCs, as they lack mitochondria and rely on glycolysis for energy.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because GLUT2 is primarily expressed in the liver and pancreas, where it plays a role in glucose sensing and regulation of glucose metabolism.
* **Option B:** This option is incorrect because GLUT4 is insulin-responsive and primarily found in adipose tissue and skeletal muscle, where it plays a key role in glucose uptake in response to insulin signaling.
* **Option C:** This option is incorrect because GLUT5 is primarily expressed in the small intestine, where it facilitates the uptake of fructose.
**Clinical Pearl / High-Yield Fact**
It's worth noting that GLUT1 is also present in the placenta, where it plays a critical role in glucose transfer from the mother to the fetus.
**Correct Answer: C. GLUT5 is a glucose transporter that is primarily found in the small intestine, where it facilitates the uptake of fructose.