Figure 1.

Pancreatic β cell. Glucose (G) is transported into the β cell by the glucose transporter, GLUT2. The resulting generation of ATP closes the K⁺_ATP channel and induces membrane depolarization and Ca²⁺ influx. This Ca²⁺ stimulates the gene expression, synthesis, and secretion of insulin and C-peptide. The stimulation of the α₂-receptor inhibits the Ca²⁺ influx and thus insulin synthesis.