Related Experiment Videos
Insulin-sensitive myelin basic protein phosphorylation on tyrosine residues
1Department of Pharmacology, University of Alabama, Birmingham 35294.
Biochemical and Biophysical Research Communications
|August 30, 1991
Summary
Researchers identified myelin basic protein (MBP) as a direct substrate for the rat brain insulin receptor tyrosine kinase. Insulin specifically enhances tyrosine phosphorylation of MBP in vitro, revealing a new signaling pathway.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Insulin receptors are present in rat brain plasma membranes.
- These receptors are associated with protein kinases capable of phosphorylating substrates like MAP2 and MBP.
Purpose of the Study:
- To investigate the role of insulin in modulating protein phosphorylation in rat brain membranes.
- To identify specific substrates for the insulin receptor tyrosine kinase in the brain.
Main Methods:
- Solubilization of rat brain plasma membranes and enrichment of glycoproteins via lectin affinity chromatography.
- In vitro kinase assays using exogenous substrates (MAP2, MBP) with and without insulin.
- Phosphoamino acid analysis to determine phosphorylation sites (tyrosine, serine, threonine).
Main Results:
- Insulin significantly stimulated myelin basic protein (MBP) phosphorylation (2.7-fold) in a dose-dependent manner (EC50 = 2 nM).
- Insulin specifically increased tyrosine phosphorylation of MBP by nearly three-fold.
- MAP2 phosphorylation was unaffected by insulin; ribosomal protein S6 was not phosphorylated under basal or insulin-stimulated conditions.
Conclusions:
- Myelin basic protein (MBP) is identified as a novel substrate for the rat brain insulin receptor tyrosine-specific protein kinase.
- This finding suggests a direct role for insulin signaling in modulating MBP phosphorylation in the brain.