Synapses are the site of chemical communication between neurons and between neurons and muscles. The synaptic vesicle (SV) is a prominent presynaptic organelle which contains chemical neurotransmitters and fuses with the plasma membrane to mediate neurotransmission. There are about 50 or so synaptic proteins which are either integral vesicle membrane proteins (e.g., synaptotagmin, syt; and syna...

Although PC12 cells express three synaptotagmin isoforms (Syts I, IV and IX), all of which have been proposed to regulate dense-core vesicle exocytosis, it remains unknown which of the Sytisoforms acts as the major Ca2+ sensor for dense-core vesicle exocytosis. In the present study, it has been shown by immunoaffinity purification and immunocytochemistry that Syts I and IX, but not Syt IV, are ...

UNLABELLED The Ca(2+) sensor synaptotagmin-1 (syt-1) regulates neurotransmitter release by interacting with anionic phospholipids. Here we test the idea that the intrinsic kinetics of syt-membrane interactions determine, in part, the time course of synaptic transmission. To tune the kinetics of this interaction, we grafted structural elements from the slowest isoform, syt-7, onto the fastest is...

Evoked and spontaneous neurotransmitter release mechanisms share similar components. Synaptotagmin-1 (Syt-1) plays a central role in evoked neurotransmitter release as a Ca sensor. Syt-1 has also been implicated in the regulation of spontaneous release. A recent study perfomed on central synapses confirms the role of Syt-1 in spontaneous release, as a Ca sensor, a fusion clamp and an inhibitor ...

BACKGROUND In neonatal binocular animals, the developing retina displays patterned spontaneous activity termed retinal waves, which are initiated by a single class of interneurons (starburst amacrine cells, SACs) that release neurotransmitters. Although SACs are shown to regulate wave dynamics, little is known regarding how altering the proteins involved in neurotransmitter release may affect w...

EXOCYTOSIS IS A GENERAL PROCESS by which intracellular vesicles containing cargo are transported to and then fuse with the plasma membrane. Exocytic vesicles either fuse constitutively or they accumulate under the plasma membrane, where they await fusion until an appropriate physiological signal is detected in a process called regulated exocytosis (4, 21). Examples of exocytic vesicles that und...

In regulated vesicle exocytosis, SNARE protein complexes drive membrane fusion to connect the vesicle lumen with the extracellular space. The triggering of fusion pore formation by Ca(2+) is mediated by specific isoforms of synaptotagmin (Syt), which employ both SNARE complex and membrane binding. Ca(2+) also promotes fusion pore expansion and Syts have been implicated in this process but the m...

Neurotransmitter release following synaptic vesicle (SV) fusion is the fundamental mechanism for neuronal communication. Synaptic exocytosis is a specialized form of intercellular communication that shares a common SNARE-mediated fusion mechanism with other membrane trafficking pathways. The regulation of synaptic vesicle fusion kinetics and short-term plasticity is critical for rapid encoding ...

Fast synchronous neurotransmitter release is triggered by calcium that activates synaptotagmin-1 (syt-1), resulting in fusion of synaptic vesicles with the presynaptic membrane. Syt-1 possesses two Ca(2+)-binding C2 domains that tether membranes via interactions with anionic phospholipids. It is capable of crosslinking membranes and has recently been speculated to trigger fusion by decreasing t...

The secretory granules (SGs) of secretory cells of the hematopoietic lineage, such as the mast cells, are lysosome-related organelles whose membrane proteins travel through the plasma membrane and the endocytic system. Therefore, a mechanism must exist to prevent proteins destined to recycling or to the trans-Golgi network (TGN) from reaching the SGs. We now show that synaptotagmin (Syt) IX, a ...