A 13-year-old adolescent boy with type 1 diabetes has a serum glucose concentration is 540 mg/dL. Several hours following IV administration of insulin, his serum glucose concentration decreases to 200 mg/dL. Which of the following mechanisms best explains the effect of the insulin signaling pathway on the GLUT4 transporter in this decrease resulting in the reduced serum glucose?

Question

Quizplus · Accepted Answer

Insulin signaling promotes the translocation of GLUT4 transporters from intracellular vesicles to the plasma membrane, increasing glucose uptake into cells and thereby reducing serum glucose levels.  Insulin-mediated glucose uptake involves activation of the kinase, PDK1. Activated PDK1 phosphorylates some isoforms of protein kinase C, PKC. The PKC isoform, PKCλ/ζ, phosphorylates intracellular vesicles containing the glucose transporter, GLUT4, resulting in their migration to and fusion with, the plasma membrane. This results in increased glucose uptake and metabolism.

A 13-Year-Old Adolescent Boy with Type 1 Diabetes Has a Serum