Protonation states at different pH, Conformational Changes and Impact of Glycosylation in Synapsin Ia

2021 ◽  
Author(s):  
Sonia Mir ◽  
Maria Saeed ◽  
Sajda Ashraf ◽  
Atta-ur Rahman ◽  
Zaheer Ul-Haq
Keyword(s):  
Neurite Outgrowth ◽  
Conformational Changes ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Synapsin I ◽  
Presynaptic Terminals ◽  
Active Zones

Synapsin I is the most abundant brain phosphoprotein present at presynaptic terminals which regulates neurotransmitter release, clustering of synaptic vesicles (SVs) at active zones, and stimulates synaptogenesis and neurite outgrowth....

scholarly journals Separation of presynaptic Cav2 and Cav1 channel function in synaptic vesicle exo- and endocytosis by the membrane anchored Ca2+ pump PMCA

2021 ◽  
Vol 118 (28) ◽  
pp. e2106621118
Author(s):  
Niklas Krick ◽  
Stefanie Ryglewski ◽  
Aylin Pichler ◽  
Arthur Bikbaev ◽  
Torsten Götz ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Neurotransmitter Release ◽  
Calcium Currents ◽  
Short Term ◽  
Triggered Release ◽  
Presynaptic Terminals ◽  
Dynamic Regulation ◽  
Short Term Plasticity ◽  
Separate Control ◽  
Active Zones

Synaptic vesicle (SV) release, recycling, and plastic changes of release probability co-occur side by side within nerve terminals and rely on local Ca2+ signals with different temporal and spatial profiles. The mechanisms that guarantee separate regulation of these vital presynaptic functions during action potential (AP)–triggered presynaptic Ca2+ entry remain unclear. Combining Drosophila genetics with electrophysiology and imaging reveals the localization of two different voltage-gated calcium channels at the presynaptic terminals of glutamatergic neuromuscular synapses (the Drosophila Cav2 homolog, Dmca1A or cacophony, and the Cav1 homolog, Dmca1D) but with spatial and functional separation. Cav2 within active zones is required for AP-triggered neurotransmitter release. By contrast, Cav1 localizes predominantly around active zones and contributes substantially to AP-evoked Ca2+ influx but has a small impact on release. Instead, L-type calcium currents through Cav1 fine-tune short-term plasticity and facilitate SV recycling. Separate control of SV exo- and endocytosis by AP-triggered presynaptic Ca2+ influx through different channels demands efficient measures to protect the neurotransmitter release machinery against Cav1-mediated Ca2+ influx. We show that the plasma membrane Ca2+ ATPase (PMCA) resides in between active zones and isolates Cav2-triggered release from Cav1-mediated dynamic regulation of recycling and short-term plasticity, two processes which Cav2 may also contribute to. As L-type Cav1 channels also localize next to PQ-type Cav2 channels within axon terminals of some central mammalian synapses, we propose that Cav2, Cav1, and PMCA act as a conserved functional triad that enables separate control of SV release and recycling rates in presynaptic terminals.

Neurotransmitter release mechanisms and microtubules

1983 ◽  
Vol 218 (1211) ◽  
pp. 253-258 ◽  
Keyword(s):  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Ordered Structure ◽  
Presynaptic Membrane ◽  
Vesicle Membrane ◽  
Ordered Arrays ◽  
The Central Nervous System ◽  
Active Zones ◽  
Dense Projections ◽  
Regular Arrays

The morphological mechanisms involved in translocation of the synaptic vesicle to the presynaptic membrane, release of transmitter from the vesicle and recycling of the vesicle membrane are still far from understood. However, there is strong evidence that vesicles move along the surfaces of a specific set of highly labile presynaptic microtubules that direct the vesicles to the active zones. These microtubules are focused in a precise geometrical array, which is in register with and in contact with presynaptic dense projections of the central nervous system synapse or presynaptic dense bars of the motor endplate. These dense complexes constitute the presynaptic grid or active zones. The regular arrays of dense projections or bars are in turn coincident with rings or chains of synaptic vesicles mobilized at release sites on the presynaptic membrane (having arrived at these precise points by microtubule translocation). Thus it is suggested that the presynaptic microtubules not only translocate synaptic vesicles, but because of their ordered arrays determine, in ontogeny, the ordered structure of the presynaptic grid.

scholarly journals Dephosphorylated synapsin I anchors synaptic vesicles to actin cytoskeleton: an analysis by videomicroscopy.

1995 ◽  
Vol 128 (5) ◽  
pp. 905-912 ◽  
Author(s):  
P E Ceccaldi ◽  
F Grohovaz ◽  
F Benfenati ◽  
E Chieregatti ◽  
P Greengard ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Synaptic Vesicle ◽  
Nerve Terminal ◽  
Actin Filaments ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Actin Polymerization ◽  
Synapsin I ◽  
Cam Kinase Ii ◽  
Cam Kinase

Synapsin I is a synaptic vesicle-associated protein which inhibits neurotransmitter release, an effect which is abolished upon its phosphorylation by Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). Based on indirect evidence, it was suggested that this effect on neurotransmitter release may be achieved by the reversible anchoring of synaptic vesicles to the actin cytoskeleton of the nerve terminal. Using video-enhanced microscopy, we have now obtained experimental evidence in support of this model: the presence of dephosphorylated synapsin I is necessary for synaptic vesicles to bind actin; synapsin I is able to promote actin polymerization and bundling of actin filaments in the presence of synaptic vesicles; the ability to cross-link synaptic vesicles and actin is specific for synapsin I and is not shared by other basic proteins; the cross-linking between synaptic vesicles and actin is specific for the membrane of synaptic vesicles and does not reflect either a non-specific binding of membranes to the highly surface active synapsin I molecule or trapping of vesicles within the thick bundles of actin filaments; the formation of the ternary complex is virtually abolished when synapsin I is phosphorylated by CaM kinase II. The data indicate that synapsin I markedly affects synaptic vesicle traffic and cytoskeleton assembly in the nerve terminal and provide a molecular basis for the ability of synapsin I to regulate the availability of synaptic vesicles for exocytosis and thereby the efficiency of neurotransmitter release.

scholarly journals Characterization of synapsin I binding to small synaptic vesicles.

1986 ◽  
Vol 261 (18) ◽  
pp. 8383-8390
Author(s):  
W Schiebler ◽  
R Jahn ◽  
J P Doucet ◽  
J Rothlein ◽  
P Greengard
Keyword(s):  
Synaptic Vesicles ◽  
Synapsin I

Distinct pools of synaptic vesicles in neurotransmitter release

Nature ◽  
1995 ◽  
Vol 375 (6531) ◽  
pp. 493-497 ◽  
Author(s):  
Vincent A. Pieribone ◽  
Oleg Shupliakov ◽  
Lennart Brodin ◽  
Sabine Hilfiker-Rothenfluh ◽  
Andrew J. Czernik ◽  
...  
Keyword(s):  
Neurotransmitter Release ◽  
Synaptic Vesicles
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