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Synapsin IIa: expression in insect cells, purification, and characterization.
Y L Siow1, T J Chilcote, F Benfenati
1Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021.
Biochemistry
|May 5, 1992
Summary
Researchers produced recombinant synapsin IIa using a baculovirus system when mammalian purification proved difficult. The recombinant protein exhibited biochemical properties similar to native synapsin IIa, including phosphorylation and synaptic vesicle binding.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Synapsins are neuron-specific phosphoproteins crucial for synaptic vesicle regulation.
- Difficulties in purifying native synapsin IIa from mammalian brains hinder biochemical studies.
Purpose of the Study:
- To produce recombinant synapsin IIa for biochemical analysis and functional studies.
- To characterize the properties of synapsin IIa produced via a baculovirus expression system.
Main Methods:
- Rat synapsin IIa cDNA was cloned into a baculovirus vector for expression in Spodoptera frugiperda (Sf9) cells.
- Recombinant synapsin IIa was purified using immunoaffinity chromatography.
- Phosphorylation studies were conducted using cAMP-dependent protein kinase and metabolic labeling.
Main Results:
- Synapsin IIa was expressed at 5% of total cellular protein in infected Sf9 cells.
- Purified recombinant synapsin IIa was phosphorylated by cAMP-dependent protein kinase.
- Phosphopeptide maps of in vitro and in vivo phosphorylated synapsin IIa were identical.
- Recombinant synapsin IIa demonstrated high-affinity, saturable binding to purified synaptic vesicles.
Conclusions:
- The baculovirus expression system is effective for producing functional recombinant synapsin IIa.
- Recombinant synapsin IIa possesses biochemical characteristics comparable to the native protein.
- These findings facilitate further investigation into synapsin IIa's physiological role in synaptic function.