synaptic membrane adhesion

Definition

Target type: biologicalprocess

The attachment of presynaptic membrane to postsynaptic membrane via adhesion molecules that are at least partially embedded in the plasma membrane. [GOC:dos]

Synaptic membrane adhesion is a crucial process in the formation and function of synapses, the specialized junctions between neurons that allow for communication. This process involves a series of molecular interactions that bring the pre- and postsynaptic membranes together, ultimately leading to the formation of a stable and functional synaptic cleft.

The adhesion process is initiated by the interaction of transmembrane proteins called cell adhesion molecules (CAMs) located on both the pre- and postsynaptic membranes. These CAMs can be classified into several families, including the neurexins, neuroligins, cadherins, and integrins. Each family exhibits distinct molecular properties and binding partners, contributing to the diversity and specificity of synaptic connections.

Neurexins and neuroligins are two key families of CAMs that play a critical role in synaptic adhesion. Neurexins are expressed on the presynaptic membrane, while neuroligins are found on the postsynaptic membrane. These proteins interact via their extracellular domains, forming trans-synaptic complexes that bridge the synaptic cleft. This interaction is highly specific, with different neurexin isoforms exhibiting preferences for specific neuroligin isoforms. The binding of neurexins and neuroligins initiates a cascade of signaling events that lead to the recruitment of other proteins to the synapse, including scaffolding proteins, signaling molecules, and cytoskeletal elements.

Cadherins are another important family of CAMs involved in synaptic adhesion. They are transmembrane proteins that interact with each other in a calcium-dependent manner, forming adherens junctions that contribute to the structural integrity of the synapse. Cadherins are involved in both pre- and postsynaptic adhesion and play a role in regulating the size and shape of the synaptic cleft.

Integrins are heterodimeric transmembrane proteins that bind to extracellular matrix (ECM) proteins, such as laminin and fibronectin. They are involved in the adhesion of the synapse to the surrounding environment and play a role in anchoring the synapse to the cytoskeleton.

Once the initial adhesion events have occurred, the synaptic cleft is further stabilized by the formation of a specialized structure called the postsynaptic density (PSD). The PSD is a dense protein complex located on the postsynaptic membrane that contains a vast array of proteins involved in signal transduction, scaffolding, and cytoskeletal organization. These proteins are recruited to the PSD by a variety of mechanisms, including direct interactions with CAMs, binding to scaffolding proteins, and diffusion from the surrounding cytoplasm.

The formation of the PSD is crucial for the proper function of the synapse. It provides a scaffold for the clustering of neurotransmitter receptors, allowing for the efficient transduction of signals from the presynaptic to the postsynaptic neuron. The PSD also plays a role in the regulation of synaptic plasticity, the ability of synapses to change their strength in response to activity.

In summary, synaptic membrane adhesion is a complex process that involves a series of molecular interactions between specialized proteins located on the pre- and postsynaptic membranes. These interactions lead to the formation of a stable and functional synaptic cleft, which is essential for neuronal communication and brain function.'
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Proteins (3)

Compounds (20)