Yotiao, a novel protein of neuromuscular junction and brain that interacts with specific splice variants of NMDA receptor subunit NR1

Ethanol tolerance and synaptic plasticity

Current concepts of the mechanisms underlying many of the pharmacological effects of ethanol on the CNS involve disruption of ion channel function via the interaction of ethanol with specific hydrophobic sites on channel subunit proteins. Of particular clinical importance is the development of tolerance and dependence to ethanol, and it is likely that adaptive changes in synaptic function in response to ethanol's actions on ion channels play a role in this process. In this article, Judson Chandler, Adron Harris and Fulton Crews discuss potential mechanisms of ethanol-induced changes in synaptic function that might provide a cellular basis for ethanol tolerance and dependence. It is proposed that multiple mechanisms are involved that include both transcriptional and post-translational modifications in NMDA and GABAA receptors.

Signals mediating ion channel clustering at the neuromuscular junction

High densities of acetylcholine receptors and sodium channels in the crests and troughs of the postsynaptic folds, respectively, ensure reliable neuromuscular signalling. Clustering of both ion channels is mediated by agrin. In the case of acetylcholine receptors, agrin activates the tyrosine kinase receptor muscle-specific kinase (MuSK), initiating a process requiring rapsyn and possibly also receptor phosphorylation. In many respects, the interactions between agrin and MuSK and their downstream effectors are atypical of conventional receptor tyrosine kinase signalling systems. A new understanding of the structural features of rapsyn involved in receptor clustering, as well as syntrophin's role in sodium channel targeting, has recently been revealed. Perhaps the most surprising result of the past year with regard to synaptogenesis is a negative one--mice lacking both dystrophin and utrophin have nearly normal neuromuscular junctions.

Molecular mechanisms of glutamate receptor clustering at excitatory synapses

The targeting of AMPA- and NMDA-type glutamate receptors to synapses in the central nervous system is essential for efficient excitatory synaptic transmission. Recent studies have indicated that protein-protein interactions of these receptors with synaptic proteins that contain PDZ domains are crucial for receptor targeting. NMDA receptors have been found to bind to the PSD-95 family of proteins, whereas AMPA receptors interact with the PDZ-domain-containing protein GRIP (glutamate receptor interacting protein). PSD-95 and GRIP contain multiple PDZ domains as well as other protein-protein interaction motifs that help to form large macromolecular complexes that may be important for the formation and plasticity of synapses.