Synapsins and the Synaptic Vesicle Reserve Pool: Floats or Anchors?

Minchuan Zhang,George J Augustine

doi:10.3390/cells10030658

Abstract

In presynaptic terminals, synaptic vesicles (SVs) are found in a discrete cluster that includes a reserve pool that is mobilized during synaptic activity. Synapsins serve as a key protein for maintaining SVs within this reserve pool, but the mechanism that allows synapsins to do this is unclear. This mechanism is likely to involve synapsins either cross-linking SVs, thereby anchoring SVs to each other, or creating a liquid phase that allows SVs to float within a synapsin droplet. Here, we summarize what is known about the role of synapsins in clustering of SVs and evaluate experimental evidence supporting these two models.

Highlights

The results indicate that complete loss of synapsins causes a selective impairment of the reserve pool (RP) [15]
2A), Milovanovic et al.336 proposed (Figure 2C). These residues are highly conserved across all synapsin (Figure synapsin molecules can condense into distinct liquid phase droplets, isoforms and thereby trap 2A), synaptic vesicles (SVs) suggesting an ability to form either homo-oligomers or hetero-oligomers
While dispersion of the clustered distal SVs by the intrinsically disordered regions (IDR) antibody is consistent with the model, it is at odds with the observation that this antibody promotes liquid phase formation in vitro

Summary

Introduction

Synapsins and the Synaptic VesicleReserve Pool: Floats or Anchors? Cells2021, 10, 658. https://doi.org/10.3390/cells10030658Academic Editor: Flavia ValtortaReceived: 22 February 2021Accepted: 11 March 2021Published: 16 March 2021Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland. These residues are highly conserved across all synapsin (Figure synapsin molecules can condense into distinct liquid phase droplets, isoforms and thereby trap 2A), SVs suggesting an ability to form either homo-oligomers or hetero-oligomers

Results

Conclusion