Question

Which of the following glucose transporters is insulin-dependent?
A) GLUT I
B) GLUT II
C) GLUT III
D) GLUT IV

Answer 1

Hint: It is a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane.

Complete Answer:
Insulin is a peptide hormone that plays a major role in the glucose homeostasis.
GLUT abbreviation for glucose transporter. It is a family of six closely related cell membrane proteins that carry glucose from the blood to cells. Slightly different glucose transporters are found in different organs (eg. In the brain, muscles).
The GLUT family is divided into three classes based on their sequence homology. The physiological roles of class I GLUTs,1,2,3 and 4 have been extensively studied for their contribution to metabolism and development.

A) GLUT I facilitate the transport of glucose across the plasma membrane. GLUT I is insulin-independent and it can meet the basic needs of muscle cells.
B) GLUT II is the principal transporter for transfer of glucose between liver and blood and it is also insulin- independent.
C) GLUT III transports glucose into brain cells at a rate that is independent of plasma level of glucose. It is also insulin- independent.
D) GLUT IV is the insulin-regulated glucose transporter found primarily in adipose tissues and striated muscles.
That means all glucose transporters have fixed areas or organs where they transport glucose either by depending on insulin or without insulin.

So the correct option is option (D) i.e. GLUT IV.

Note: Hence it is clear now that GLUTS I, II and III are insulin-independent whereas GLUT IV is insulin-dependent glucose transporter. GLUT4 is an insulin-regulated glucose transporter which is responsible for insulin-regulated glucose uptake into fat and muscle cells. It is mainly found in intracellular vesicles considered as GLUT4 storage vesicles.