What is the Km value characteristic of GLUT 4?

The Km value for GLUT 4 is low, indicating that this glucose transporter has a high affinity for glucose. This means that GLUT 4 effectively transports glucose into cells even when glucose concentrations are relatively low, which is particularly important in tissues such as muscle and adipose tissue where glucose uptake must occur rapidly, especially in response to insulin.

A low Km reflects the transporter’s ability to bind glucose tightly, allowing for efficient uptake under physiological conditions, especially after a meal when insulin is released and promotes the translocation of GLUT 4 to the cell membrane. This characteristic is essential for maintaining glucose homeostasis in the body and enabling cells to respond effectively to insulin signaling.

In contrast, other transporters with high Km values would require higher glucose concentrations for effective transport, which is not optimal for the tissues that rely on GLUT 4 for glucose uptake. Thus, the low Km of GLUT 4 plays a crucial role in its function within glucose metabolism and energy regulation.