A novel synaptic vesicle-associated phosphoprotein: SVAPP-120

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Synaptic vesicles are crucial for neurotransmission.
• Identifying their associated proteins aids understanding of synaptic function.
• Previous research has characterized key synaptic vesicle proteins like synapsin I and synaptophysin.

Purpose of the Study:

• To identify and characterize novel proteins associated with highly purified rat brain synaptic vesicles.
• To investigate the properties and expression patterns of a newly identified protein doublet, SVAPP-120.
• To confirm the presence of other known proteins like aldolase and alpha c-adaptin on synaptic vesicles.

Main Methods:

• Generation of polyclonal antibodies against synaptic vesicle proteins.
• Purification of synaptic vesicles from rat brain.
• Western blotting and direct protein sequencing.
• High salt extraction to determine membrane association.
• Analysis of protein expression during postnatal development.

Main Results:

• A novel phosphoprotein doublet, synaptic vesicle-associated phosphoprotein with a molecular mass of 120 kDa (SVAPP-120), was identified.
• SVAPP-120 copurifies with synaptic vesicles, is brain-specific, and its expression correlates with synaptogenesis.
• SVAPP-120 is a serine/threonine phosphoprotein and is not an integral membrane protein.
• Aldolase and alpha c-adaptin were also identified on purified synaptic vesicles.

Conclusions:

• SVAPP-120 represents a novel synaptic vesicle-associated phosphoprotein.
• Its characteristics suggest a role in synaptic vesicle function and development.
• Direct protein sequencing confirmed the presence of glycolytic and clathrin-related proteins on synaptic vesicles.