By virtue of their protein interactions, shank proteins assemble signaling platforms for gproteinmediated signaling and the control of calcium. Immunocytochemical localization of the postsynaptic density. Request pdf scaffold proteins in the postsynaptic density many intractable neurological and mental diseases, including epilepsy, depression, and. Sep 15, 2009 smooth er, smooth endoplasmic reticulum. The shank family comprises three large multidomain proteins playing central roles as protein scaffolds in the neuronal postsynaptic density. Shank proteins are multidomain scaffold proteins of the postsynaptic density, connecting neurotransmitter receptors and other membrane proteins with signaling proteins and the actin cytoskeleton. We here present a quantitative characterization of the kinetics and affinity of interactions between gpcrs and one of the best characterized pdz scaffold proteins, postsynaptic density protein 95 psd95, using fluorescence polarization fp and surface plasmon resonance spr. Psd through binding the postsynaptic density95, discs large, zona occludens1 pdz domain membraneassociated guanylate kinase maguk scaffold proteins postsynaptic density95 psd95 and synapseassociated protein97 sap97 colledge et al.
Oct 19, 2016 at synapses of central neurons, the importance of scaffold proteins is exemplified in the postsynaptic density psd, a highly organised structure consisting of multiple densely packed interacting. After transformation, the cells were grown at 30c to an optical density of 0. The addition of receptors is regulated by a set of enzymes held near the membrane of the synapse by a protein scaffold known as the postsynaptic density. Here, we demonstrate that mixing purified postsynaptic scaffold proteins at physiological concentrations can form highly condensed, selforganized psdlike assemblies via liquidliquid phase separation llps. A major scaffold protein called psd95 contains binding sites, known as pdz domains, that hold protein receptors and regulatory enzymes in place. The postsynaptic architecture of excitatory synapses. A relevant role of postsynaptic density proteins with scaffolding and association function has been recognized also in receptor diffusion that, together with endocytosis and exocytosis, is a crucial mechanism regulating the movement of receptors in the postsynaptic membrane during plasticity blanpied et al.
Synapseassociated proteins are the scaffold for the selective aggregation of ion channels at synapses. As protein detection technologies have increased in sensitivity, such as with. These postsynaptic scaffold proteins, such as postsynaptic density95 psd95 and homer proteins, link glutamate receptors and intracellular modulators, facilitating glutamate receptor transmission and participating in the etiology of neurological diseases 16. Scaffold proteins in the postsynaptic density springerlink. Pdf scaffolding proteins of the postsynaptic density.
Psd95 family maguks are essential for anchoring ampa. B core scaffold proteins of the psd psd95, gkap, shank, and homer interact with each other and other proteins as indicated by overlap of protein shapes and are thought to form a lattice for the assembly of postsynaptic membrane proteins and signaling molecules. The postsynaptic density is comprised of membrane receptors and ion channels, scaffold and adaptor proteins, signalling proteins, celladhesion molecules and components of the cytoskeleton. Since the title of this presentation covers a very broad topic, i will not be able to discuss all aspects in great detail, so i will focus on excitatory synapses, and beyond that i will focus mainly on three multidomain scaffold proteins called grip, psd95, and shank. Thus this proteomic study reveals crucial information about molecular abundance as well as molecular diversity in the psd, and provides a basis for further studies on the molecular mechanisms of synaptic function and plasticity. Phosphorylation state of postsynaptic density proteins. Reconstituted postsynaptic density as a molecular platform. Highly specific and selective isotope dilution mass spectrometry assays were developed using isotopically labeled polypeptide concatemer internal standards.
Scaffolding proteins of the postsynaptic density contribute to synaptic plasticity by regulating receptor localization and distribution. Immunocytochemical localization of the postsynaptic. How maguks underlie synaptic strength at the molecular level is still not well understood. Pdf postsynaptic density proteins and their involvement. Downregulation of postsynaptic density95interacting. The distribution of irsp53 at the psd in cultured hippocampal neurons was examined under basal and excitatory conditions by immunoelectron microscopy. Psd95 family maguks are essential for anchoring ampa and. Postsynaptic density proteins and their involvement in. The postsynaptic scaffold proteins prosap1shank2 and homer1 are associated with glutamate receptor complexes at rat retinal synapses. For instance, palmitoylation and depalmitoylation of the central postsynaptic scaffold protein postsynaptic density95 psd95 is important for synaptic plasticity. Quantitative studies are presented of postsynaptic density psd fractions from rat cerebral cortex with the ultimate goal of defining the average copy numbers of proteins in the psd complex.
Scaffold proteins in the postsynaptic density request pdf. The postsynaptic density psd at glutamatergic synapses is a macromolecular complex of various molecules that organize the different glutamate receptors spatially and link them to their appropriate downstream signaling pathways and to the cytoskeleton. Unconventional sh3 domain from the postsynaptic density scaffold protein shank3. Synaptic activity induces growth and structural rearrangements of the psd and dynamic turnover of psd. Irsp53 baiap2 is an abundant protein at the postsynaptic density psd that binds to major psd scaffolds, psd95 and shanks, as well as to factin. The postsynaptic site of the excitatory asymmetric synapse is characterized by an electrondense structure known as the postsynaptic density psd, which is attached to the postsynaptic membrane. The postsynaptic density and dendritic raft localization of. Key role of the postsynaptic density scaffold proteins shank. Moreover, they link postsynaptic receptors with their downstream signaling proteins and regulate the. Key role of the postsynaptic density scaffold proteins. In particular, scaffolding proteins localized to the postsynaptic density in actinrich spines along dendrites provide potential targets for compartmentalized regulation of ionchannel function and the possibility that their distribution is modulated by ethanol at synapses, contributing to the development of alcohol tolerance chandler, 2003. They play a major role in many synaptic functions including the trafficking, anchoring, and clustering of. The postsynaptic density of excitatory synapses is especially complex and dynamic in composition and regulation. Localized to the postsynaptic membrane of spines is the postsynaptic density psd, a complex protein apparatus comprised of glutamate receptors, associated scaffold and cytoskeletal proteins, and signal transduction molecules.
Scaffold proteins at the postsynaptic density springerlink. Many proteins in the psd are involved in the regulation of synaptic function. Role of palmitoylation of postsynaptic proteins in. Here, they act as adaptor proteins between neurotransmitter receptors and the microtubule. They play a major role in many synaptic functions including the trafficking, anchoring, and clustering of glutamate receptors and adhesion molecules. The postsynaptic density psd is a huge protein complex associated with postsynaptic membranes of excitatory synapses. Key among these, are postsynaptic density 95 psd95, neuroligin a cellular adhesion molecule, nmda receptors, ampa receptors, calciumcalmodulindependent protein kinase ii and actin. Such psd scaffold condensates can cluster glutamate receptors, enrich synaptic enzymes, and promote actin bundle formation. The cells were pelleted by centrifugation at 50003 g for 10 min and. Regulated degradation of postsynaptic density psd proteins by the ubiquitinproteasome system is believed to play an important role in activitydependent synaptic remodeling. The shank proteins are closely linked to neuropsychiatric diseases, such as autism spectrum disorders. Organization and dynamics of pdzdomainrelated supramodules.
Psd, postsynaptic density sam, sterile alpha motif sh3, src. They build preformed assemblies that are precisely anchored at sites of cellcell contact e. Though poorly defined in traditionally prepared thinsection electron micrographs, the pallium becomes denser and more conspicuous during intense synaptic activity, due to the. The psd, which is linked to glutamate receptors, forms a postsynaptic protein lattice composed of numerous psd scaffold and cytoskeletal proteins and. Pdz domainmediated interactions of g proteincoupled. Under basal conditions, label for irsp53 is concentrated at the psd. Pdf scaffold proteins at the postsynaptic density michael. Previous studies have shown that overexpression in hippocampal neurons of two postsynaptic density psd scaffold proteins, shank1b and homer1b, induces spine maturation, including. With psd93 it is recruited into the same nmda receptor and potassium channel clusters.
The postsynaptic density protein psd95 is an important scaffolding molecule regulating the localization of nmdars and ampars at the postsynaptic membrane. The postsynaptic density psd is an electrondense structure located at the synaptic contacts between neurons. Though poorly defined in traditionally prepared thinsection electron micrographs, the pallium becomes denser and more conspicuous during. Psd95 is a member of the membraneassociated guanylate kinase maguk family. The postsynaptic density psd contains the glutamate receptors that detect the release of glutamate from the presynaptic terminal and a host of associated signaling molecules that transduce glutamate binding into postsynaptic biochemical responses. This interaction underlies kv channel clustering at unique membrane sites and is important for the proper assembly and functioning of the synapse. Postsynaptic scaffold proteins in health and disease hstalks. Stimulating neuronal activity in vitro and in vivo induces the ubiquitination and degradation of gkapsapap and shank, major scaffold proteins of the psd. Previous studies have shown that overexpression in hippocampal neurons of two postsynaptic density psd scaffold proteins, shank1b and homer1b, induces spine maturation, including translocation of the intracellular. Psd95 postsynaptic density protein 95 also known as sap90 synapseassociated protein 90 is a protein that in humans is encoded by the dlg4 discs large homolog 4 gene psd95 is a member of the membraneassociated guanylate kinase maguk family.
Psd95 postsynaptic density protein 95 also known as sap90 synapseassociated protein 90 is a protein that in humans is encoded by the dlg4 discs large homolog 4 gene. Quantitative mass spectrometry measurements reveal. Scaffold proteins are abundant and essential components of the postsynaptic density psd. Psd95 is known to be ubiquitinated by the e3 ligase mdm2 murine double minute and degraded via the ubiquitin proteasome pathway in response to nmda receptor activation figure 3a 15. The localization of the postsynaptic density protein psd95 was studied. In excitatory synapses of the brain, the postsynaptic density. Synaptic activity induces growth and structural rearrangements of the psd and dynamic turnover of psd proteins. In mammals, the psd is composed of more than 1,000 proteins including receptors, scaffold proteins, signalling enzymes and cytoskeletal proteins. Three shank proteins shank1, shank2, and shank3 have been identified in mammals. At synapses of central neurons, the importance of scaffold proteins is exemplified in the postsynaptic density psd, a highly organised structure consisting of multiple densely packed interacting. The postsynaptic scaffold proteins prosap1shank2 and homer1. The postsynaptic density and dendritic raft localization. Asd, autism spectrum disorder az, active zone psd, postsynaptic density sam, sterile alpha motif sh3, src.
Kennedy1 1division of biology, california institute of technology, pasadena, california 91125, 2european molecular biology laboratory, d69012 heidelberg, germany, and 3mclaughlin. The postsynaptic density psd of excitatory synapses is a membraneassociated megaorganelle that is highly enriched in glutamate receptors and their downstream signalling proteins. The postsynaptic scaffold proteins prosap1shank2 and. Association of an akinaseanchoring protein signaling. Ubiquitination of neurotransmitter receptors and postsynaptic. Scaffold proteins at the postsynaptic density request pdf. View enhanced pdf access article on wiley online library html view download pdf for. I will start off by introducing some basic concepts about synapses, their plasticity, their molecular organization.
Degradation of postsynaptic scaffold gkap and regulation. The postsynaptic density psd 95 family of membraneassociated guanylate kinases maguks are major scaffolding proteins at the psd in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. These four scaffold proteins serve to connect the transmembrane ion channels and receptors on the postsynaptic plasma membranes to the actin cytoskeleton at the interface between psd and spine. Solution structures of the sh3 domains from shank scaffold. Irsp53 accumulates at the postsynaptic density under. Psd proteins are crucial for synaptic transmission and plasticity.
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