B9-serine residue is crucial for insulin actions in glucose metabolism

Aim: To explore the importance of B9 and B10 amino acid residues in the insulin molecule. Methods: The [B9Glu, B10Asp] insulin (E,D-insulin) receptor binding activity, glucose upta ke activity, and lipogenesis activity were measured in isolated adipocytes. The translocation of glucose transporter 4 (Glut4) and the phosphorylation of insulin receptor (IR) stimulated by E, D-insulin were determined by Western blotting. Results: Compared with native insulin, the receptor binding activity of E,D-insulin was 31 %; the stimulating activity of E,D-insulin in glucose transport and lipogenesis were 45 % and 40 % respectively; the stimulations of Glut4 translocation and insulin receptor autophosphorylation of E,D-insulin were about 58 % and 46 % respectively. Conclusion: B9-serine residue is crucial for insulin actions in glucose metabolism.