Figure 1: Basic mechanism of insulin secretion and sequential mechanistic pathway of BV (melittin) leading to an increase in insulin secretion in pancreatic β-cells. (A) Blood glucose (5 mM in concentration) enters the β-cell through the glucose transporter (GLUT2). (B) ATP production rapidly occurs as a result of glycolysis and respiration. (C) Then, ATP-sensitive K+ channels are closed, and K+ efflux is inhibited. (D) Consequently, plasma membrane depolarizes, and (E) voltage-gated Ca2+ channels open. Finally, Ca2+ influx increases, which triggers exocytosis of insulin granules. ① Melittin directly depolarizes the cell membrane, ② it increases Ca2+ inflow into the cell, ③ it promotes more granule secretion, and ④ it increases insulin secretion into the blood stream. Note: phosphorus: P; calcium: Ca2+. Adapted from