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Hormone-induced conformational changes in the hepatic insulin receptor
The Journal of Biological Chemistry
|August 10, 1983
Summary
Insulin receptor affinity changes upon hormone binding, altering its structure and sensitivity to trypsin. These conformational changes influence insulin binding and receptor processing in liver membranes.
Area of Science:
- Biochemistry
- Cell Biology
- Endocrinology
Background:
- The insulin receptor exists in low and high affinity states.
- Hormone binding shifts equilibrium towards the high affinity state.
Purpose of the Study:
- To investigate conformational changes in the insulin receptor upon hormone binding.
- To determine the effect of these changes on receptor structure and proteolysis.
Main Methods:
- Covalent coupling of 125I-insulin to receptor alpha subunits.
- Trypsin digestion of occupied and unoccupied insulin receptors.
- Analysis of receptor fragment sizes and tryptic lability.
Main Results:
- Hormone binding leads to increased 125I-insulin coupling to higher affinity receptors.
- Trypsin digestion reveals two distinct conformational changes in the insulin receptor.
- Extended incubation results in receptor degradation and altered tryptic sensitivity.
Conclusions:
- Insulin receptor affinity modulation involves rapid and slow conformational changes.
- These changes affect receptor susceptibility to proteolysis and hormone binding.
- Further research is needed to understand the significance of receptor degradation products.