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ACTH, cyclic nucleotides, and brain protein phosphorylation in vitro
H Zwiers1, H D Veldhuis, P Schotman
1Division of Molecular Neurobiology Rudolf Magnus Institute for Pharmacology Laboratory of Physiological Chemistry, Medical Faculty Institute of Molecular Biology, State University of Utrecht, Padualaan 8, Utrecht, The Netherlands.
Neurochemical Research
|November 26, 2013
Summary
Cyclic AMP (cAMP) enhances protein phosphorylation in rat brain synaptosomes. The peptide ACTH1-24 also affects protein phosphorylation, showing a biphasic effect at specific concentrations.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Synaptosomal plasma membranes are crucial for neuronal function.
- Protein phosphorylation plays a key role in signal transduction pathways.
- Cyclic AMP (cAMP) is a vital second messenger in cellular signaling.
Purpose of the Study:
- To investigate endogenous protein phosphorylation in rat brain synaptosomes.
- To examine the effect of cyclic AMP (cAMP) on protein phosphorylation.
- To determine the influence of the peptide ACTH1-24 on synaptosomal protein phosphorylation.
Main Methods:
- In vitro study of endogenous protein phosphorylation.
- Utilized rat brain synaptosomal plasma membranes.
- Measured (32)P incorporation into proteins.
- Applied varying concentrations of ACTH1-24 (10(-10) to 10(-4) M).
Main Results:
- Cyclic AMP (cAMP) significantly stimulated (32)P incorporation in three protein bands (75,000, 57,000, and 54,000 Da).
- ACTH1-24 exhibited a biphasic effect on protein phosphorylation.
- Lower concentrations of ACTH1-24 (around 10(-8) M) significantly decreased phosphorylation, while higher concentrations (10(-4)-10(-5) M) also reduced it.
- ACTH1-24 affected phosphoprotein bands with lower molecular weights compared to cAMP.
Conclusions:
- Endogenous protein phosphorylation in rat brain synaptosomes is modulated by both cAMP and ACTH1-24.
- ACTH1-24 exerts a concentration-dependent, biphasic influence on protein phosphorylation.
- The distinct molecular weights of affected phosphoprotein bands suggest different signaling pathways are involved.
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