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Regulation of insulin receptor kinase activity by insulin mimickers and an insulin antagonist
Abstract:
Three agents which mimic insulin action in intact cells (concanavalin A, wheat germ agglutinin, and polyclonal insulin receptor antibody), mimicked insulin's ability to stimulate the kinase activity of purified insulin receptors. In contrast, monoclonal insulin receptor antibody, an antagonist of insulin action, did not stimulate the phosphorylation of the insulin receptor either in intact IM-9 cells or in purified receptor preparations. This antibody, however, antagonized the ability of insulin to stimulate the phosphorylation of the receptor both in intact cells and in the purified receptor. These studies with insulin mimickers and an insulin antagonist are consistent with a role for the kinase activity of the receptor mediating the actions of insulin.
Insights
Agents mimicking insulin action stimulated insulin receptor kinase activity. An insulin antagonist antibody blocked insulin
Area of Science:
- Biochemistry
- Cell Biology
- Endocrinology
Background:
- Insulin is a key metabolic hormone.
- Insulin exerts its effects by binding to the insulin receptor.
- The insulin receptor possesses intrinsic tyrosine kinase activity.
Purpose of the Study:
- To investigate the role of insulin receptor kinase activity in mediating insulin's actions.
- To determine if insulin mimickers and antagonists affect receptor kinase activity.
Main Methods:
- Used concanavalin A, wheat germ agglutinin, and polyclonal insulin receptor antibody as insulin mimickers.
- Utilized a monoclonal insulin receptor antibody as an insulin antagonist.
- Assessed the kinase activity of purified insulin receptors and phosphorylation in intact IM-9 cells.
Main Results:
- Insulin mimickers stimulated the kinase activity of purified insulin receptors.
- The monoclonal insulin receptor antibody did not stimulate receptor phosphorylation.
- The monoclonal antibody antagonized insulin's ability to stimulate receptor phosphorylation in both intact cells and purified preparations.
Conclusions:
- The kinase activity of the insulin receptor plays a crucial role in mediating insulin's cellular actions.
- These findings support a model where receptor autophosphorylation is a key step in insulin signal transduction.