User:David L. Nelson/Sandbox 9

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Contents 1 Insulin 1.1 Introduction 1.2 PDB Entry 1.3 Structure 1.4 Role in Diabetes

Insulin

Introduction

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The major function of Insulin is to counter the action of a number of blood sugar generating hormones and to maintain low glucose levels. Because there are numerous high blood sugar hormones, disorders associated with insulin usually lead to severe high blood sugar and other complications.

In addition to its role in regulating glucose metabolism, insulin brings about the creating of fat cells, decreases the breakdown of lipids, and increases amino acid transport into cells. Insulin also regulates transcription and stimulates growth, DNA synthesis, and cell replication.

Insulin is synthesized in the β-cells of the islets of Langerhans. Its signal peptide is folded to its basic structure and locked in this conformation by the formation of 2 disulfide bonds. Insulin secretion from β-cells is principally regulated by glucose levels. Increased uptake of glucose by pancreatic β-cells leads to a complementary increase in metabolism. The increase in metabolism leads to the inhibition of an ATP-sensitive potassium channel (KATP channel). The net result is insulin secretion. This role of KATP channels in insulin secretion presents a target for treating high blood sugar due to insulin insufficiency as is typical in type 2 diabetes.

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PDB Entry

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Structure

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spinqualitylabelsall models human insulin dimer (1APH) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

To the right is the tertiary structure of insulin. This tertiary structure is characterized by the , which are highlighted in red. These sulfide bonds have important roles in insulin, specifically in the processes of order and compactness of the structure.

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Role in Diabetes

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