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Insulin receptor autophosphorylation occurs asymmetrically
1Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118.
The Journal of Biological Chemistry
|February 25, 1993
Summary
A novel insulin analogue revealed that insulin receptor autophosphorylation is asymmetric. One receptor half incorporates more phosphate, despite similar phosphorylation sites and kinetics, suggesting a new activation model.
Area of Science:
- Biochemistry
- Cell Signaling
- Molecular Biology
Background:
- The insulin receptor is a dimer with alpha and beta subunits.
- A novel insulin analogue (BBpa insulin) was developed to study receptor behavior.
- Previous studies showed BBpa insulin binding stimulates receptor autophosphorylation.
Purpose of the Study:
- To investigate the symmetry of insulin receptor autophosphorylation.
- To understand the mechanism of insulin receptor activation.
Main Methods:
- Utilizing a novel insulin analogue (BBpa insulin) as a probe.
- Measuring orthophosphate incorporation into receptor halves.
- Employing phosphopeptide mapping to analyze phosphorylation sites.
Main Results:
- The uncoupled receptor half incorporated 50% more orthophosphate than the coupled half.
- Phosphorylation sites and kinetics were similar between both receptor halves.
- Phosphate incorporation patterns remained consistent across different time points and ATP concentrations.
Conclusions:
- Insulin receptor autophosphorylation occurs in an asymmetric manner.
- Binding of a single insulin molecule can initiate asymmetric autophosphorylation.
- A new model for insulin receptor activation is proposed based on asymmetric signaling.