The Experts below are selected from a list of 342 Experts worldwide ranked by ideXlab platform
Leslie P Tolbert - One of the best experts on this subject based on the ideXlab platform.
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EGFR and IgCAM localization probed by sucrose gradient flotation of detergent resistant membranes.
2013Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:ALs were separated from brains and homogenized separately. Detergent-resistant and detergent-soluble membranes were separated by sucrose step-gradient flotation. Detergent resistant membranes were found in the 25% sucrose layer and at the 30−35% sucrose interface, while detergent soluble membranes were found in the 40 and 60% sucrose layers. Associated proteins were separated via PAGE and transferred to a PVDF membrane for immunoblotting. Using an antibody to activated EGFR, dimers (250 kDa) were found mostly in a detergent-resistant fraction at the 30−35% sucrose interface, smaller amounts were found in the 25% and 40+60% sucrose layers. For blots probed with an antibody to M sexta neuroglian, only the 30−35% sucrose interface fraction produced a band. As for the pEGFR blot, the TM-Fas II blot produced bands for all three fractions, with the 30−35% interface labeled more intensely than the other two fractions. An antibody to GPI-linked Fasciclin II, expected to be raft-associated by virtue of its GPI anchor, labeled only the 25% sucrose and the 30-35% sucrose interface fractions.
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Blocking glial FGFR activation leads to abnormal fasciculation of ORN axons in the sorting zone.
2012Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:Control and PD173074-treated animals were allowed to develop to stage 6–7, then dissected and their brains labeled with an antibody to M. sexta Fasciclin II in order to visualize the distribution of a known subset of ORN axons. A: In control animals, ORN axons normally exhibit significant changes in fasciculation (relative to their state in the antennal nerve) a short distance into the sorting zone. B: PD173074-treated animals exhibited unchanged fasciculation in traveling through the sorting zone, although they did show increased fasciculation on exiting the sorting zone (arrowheads). Projection depths = 35 µm in A, 45 µm in B.
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Diagram showing the basic cellular elements of an adult antennal lobe in Manduca sexta.
2012Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:A: Olfactory receptor neurons (ORNs) located in the antennae extend axons (green) to the antennal lobes of the brain where they end in structures called glomeruli and synapse with antennal lobe neurons. Two classes of AL neurons, local interneurons (ln) and projection neurons (pn), have their cell bodies in clusters called the lateral and medial groups (LG & MG), which reside outside of the antennal lobe neuropil. B: Labeling of an untreated female antennal lobe (AL) at stage 7 with an antibody to M. sexta Fasciclin II (orange) and a nucleic acid dye (Syto 13, blue) makes clear the major changes in ORN axon fasciculation and direction a short distance into the sorting zone (SZ), with axons exiting the sorting zone in large MFas II-positive bundles. Projection depth = 15 µm. C: A single glomerulus, showing the relationship of ORN axon terminals and AL neuron dendrites. ORN axons form a nerve layer around the outside of the antennal lobe neuropil, then turn sharply and extend through the glial layer and branch in the outer portion of a glomerulus in the glomerular layer. The cell bodies and processes of neuropil (NP) glial cells form a nearly complete envelope around each glomerulus. Panels A and C adapted from [33].
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Activation of Glial FGFRs Is Essential in Glial Migration, Proliferation, and Survival and in Glia-Neuron Signaling during Olfactory System Development
2012Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:Development of the adult olfactory system of the moth Manduca sexta depends on reciprocal interactions between olfactory receptor neuron (ORN) axons growing in from the periphery and centrally-derived glial cells. Early-arriving ORN axons induce a subset of glial cells to proliferate and migrate to form an axon-sorting zone, in which later-arriving ORN axons will change their axonal neighbors and change their direction of outgrowth in order to travel with like axons to their target areas in the olfactory (antennal) lobe. These newly fasciculated axon bundles will terminate in protoglomeruli, the formation of which induces other glial cells to migrate to surround them. Glial cells do not migrate unless ORN axons are present, axons fail to fasciculate and target correctly without sufficient glial cells, and protoglomeruli are not maintained without a glial surround. We have shown previously that Epidermal Growth Factor receptors and the IgCAMs Neuroglian and Fasciclin II play a role in the ORN responses to glial cells. In the present work, we present evidence for the importance of glial Fibroblast Growth Factor receptors in glial migration, proliferation, and survival in this developing pathway. We also report changes in growth patterns of ORN axons and of the dendrites of olfactory (antennal lobe) neurons following blockade of glial FGFR activation that suggest that glial FGFR activation is important in reciprocal communication between neurons and glial cells.
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Activation of Glial FGFRs Is Essential in Glial Migration, Proliferation, and Survival and in Glia-Neuron Signaling during Olfactory System Development
2012Co-Authors: Nicholas J Gibson, Leslie P TolbertAbstract:Development of the adult olfactory system of the moth Manduca sexta depends on reciprocal interactions between olfactory receptor neuron (ORN) axons growing in from the periphery and centrally-derived glial cells. Early-arriving ORN axons induce a subset of glial cells to proliferate and migrate to form an axon-sorting zone, in which later-arriving ORN axons will change their axonal neighbors and change their direction of outgrowth in order to travel with like axons to their target areas in the olfactory (antennal) lobe. These newly fasciculated axon bundles will terminate in protoglomeruli, the formation of which induces other glial cells to migrate to surround them. Glial cells do not migrate unless ORN axons are present, axons fail to fasciculate and target correctly without sufficient glial cells, and protoglomeruli are not maintained without a glial surround. We have shown previously that Epidermal Growth Factor receptors and the IgCAMs Neuroglian and Fasciclin II play a role in the ORN responses to glial cells. In the present work, we present evidence for the importance of glial Fibroblast Growth Factor receptors in glial migration, proliferation, and survival in this developing pathway. We also report changes in growth patterns of ORN axons and of the dendrites of olfactory (antennal lobe) neurons following blockade of glial FGFR activation that suggest that glial FGFR activation is important in reciprocal communication betwee
Nicholas J Gibson - One of the best experts on this subject based on the ideXlab platform.
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EGFR and IgCAM localization probed by sucrose gradient flotation of detergent resistant membranes.
2013Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:ALs were separated from brains and homogenized separately. Detergent-resistant and detergent-soluble membranes were separated by sucrose step-gradient flotation. Detergent resistant membranes were found in the 25% sucrose layer and at the 30−35% sucrose interface, while detergent soluble membranes were found in the 40 and 60% sucrose layers. Associated proteins were separated via PAGE and transferred to a PVDF membrane for immunoblotting. Using an antibody to activated EGFR, dimers (250 kDa) were found mostly in a detergent-resistant fraction at the 30−35% sucrose interface, smaller amounts were found in the 25% and 40+60% sucrose layers. For blots probed with an antibody to M sexta neuroglian, only the 30−35% sucrose interface fraction produced a band. As for the pEGFR blot, the TM-Fas II blot produced bands for all three fractions, with the 30−35% interface labeled more intensely than the other two fractions. An antibody to GPI-linked Fasciclin II, expected to be raft-associated by virtue of its GPI anchor, labeled only the 25% sucrose and the 30-35% sucrose interface fractions.
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Blocking glial FGFR activation leads to abnormal fasciculation of ORN axons in the sorting zone.
2012Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:Control and PD173074-treated animals were allowed to develop to stage 6–7, then dissected and their brains labeled with an antibody to M. sexta Fasciclin II in order to visualize the distribution of a known subset of ORN axons. A: In control animals, ORN axons normally exhibit significant changes in fasciculation (relative to their state in the antennal nerve) a short distance into the sorting zone. B: PD173074-treated animals exhibited unchanged fasciculation in traveling through the sorting zone, although they did show increased fasciculation on exiting the sorting zone (arrowheads). Projection depths = 35 µm in A, 45 µm in B.
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Diagram showing the basic cellular elements of an adult antennal lobe in Manduca sexta.
2012Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:A: Olfactory receptor neurons (ORNs) located in the antennae extend axons (green) to the antennal lobes of the brain where they end in structures called glomeruli and synapse with antennal lobe neurons. Two classes of AL neurons, local interneurons (ln) and projection neurons (pn), have their cell bodies in clusters called the lateral and medial groups (LG & MG), which reside outside of the antennal lobe neuropil. B: Labeling of an untreated female antennal lobe (AL) at stage 7 with an antibody to M. sexta Fasciclin II (orange) and a nucleic acid dye (Syto 13, blue) makes clear the major changes in ORN axon fasciculation and direction a short distance into the sorting zone (SZ), with axons exiting the sorting zone in large MFas II-positive bundles. Projection depth = 15 µm. C: A single glomerulus, showing the relationship of ORN axon terminals and AL neuron dendrites. ORN axons form a nerve layer around the outside of the antennal lobe neuropil, then turn sharply and extend through the glial layer and branch in the outer portion of a glomerulus in the glomerular layer. The cell bodies and processes of neuropil (NP) glial cells form a nearly complete envelope around each glomerulus. Panels A and C adapted from [33].
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Activation of Glial FGFRs Is Essential in Glial Migration, Proliferation, and Survival and in Glia-Neuron Signaling during Olfactory System Development
2012Co-Authors: Nicholas J Gibson, Leslie P Tolbert, Lynne A OlandAbstract:Development of the adult olfactory system of the moth Manduca sexta depends on reciprocal interactions between olfactory receptor neuron (ORN) axons growing in from the periphery and centrally-derived glial cells. Early-arriving ORN axons induce a subset of glial cells to proliferate and migrate to form an axon-sorting zone, in which later-arriving ORN axons will change their axonal neighbors and change their direction of outgrowth in order to travel with like axons to their target areas in the olfactory (antennal) lobe. These newly fasciculated axon bundles will terminate in protoglomeruli, the formation of which induces other glial cells to migrate to surround them. Glial cells do not migrate unless ORN axons are present, axons fail to fasciculate and target correctly without sufficient glial cells, and protoglomeruli are not maintained without a glial surround. We have shown previously that Epidermal Growth Factor receptors and the IgCAMs Neuroglian and Fasciclin II play a role in the ORN responses to glial cells. In the present work, we present evidence for the importance of glial Fibroblast Growth Factor receptors in glial migration, proliferation, and survival in this developing pathway. We also report changes in growth patterns of ORN axons and of the dendrites of olfactory (antennal lobe) neurons following blockade of glial FGFR activation that suggest that glial FGFR activation is important in reciprocal communication between neurons and glial cells.
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Activation of Glial FGFRs Is Essential in Glial Migration, Proliferation, and Survival and in Glia-Neuron Signaling during Olfactory System Development
2012Co-Authors: Nicholas J Gibson, Leslie P TolbertAbstract:Development of the adult olfactory system of the moth Manduca sexta depends on reciprocal interactions between olfactory receptor neuron (ORN) axons growing in from the periphery and centrally-derived glial cells. Early-arriving ORN axons induce a subset of glial cells to proliferate and migrate to form an axon-sorting zone, in which later-arriving ORN axons will change their axonal neighbors and change their direction of outgrowth in order to travel with like axons to their target areas in the olfactory (antennal) lobe. These newly fasciculated axon bundles will terminate in protoglomeruli, the formation of which induces other glial cells to migrate to surround them. Glial cells do not migrate unless ORN axons are present, axons fail to fasciculate and target correctly without sufficient glial cells, and protoglomeruli are not maintained without a glial surround. We have shown previously that Epidermal Growth Factor receptors and the IgCAMs Neuroglian and Fasciclin II play a role in the ORN responses to glial cells. In the present work, we present evidence for the importance of glial Fibroblast Growth Factor receptors in glial migration, proliferation, and survival in this developing pathway. We also report changes in growth patterns of ORN axons and of the dendrites of olfactory (antennal lobe) neurons following blockade of glial FGFR activation that suggest that glial FGFR activation is important in reciprocal communication betwee
Morgan Sheng - One of the best experts on this subject based on the ideXlab platform.
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requirement of n terminal cysteines of psd 95 for psd 95 multimerization and ternary complex formation but not for binding to potassium channel kv1 4
Journal of Biological Chemistry, 1999Co-Authors: Yiping Hsueh, Morgan ShengAbstract:The PSD-95 family of PSD-95/Discs large/ZO-1 (PDZ) domain-containing proteins plays a role in the clustering and localization of specific ion channels and receptors at synapses. Previous studies have shown that PSD-95 forms multimers through an N-terminal region (termed the N-segment) and that the multimerization of PSD-95 is critical for its ability to cluster Shaker-type potassium channel Kv1.4 in heterologous cells. We show here that the PSD-95 N-segment functions as a multimerization domain only when located at the N-terminal end of a heterologous protein. A pair of N-terminal cysteines, Cys3 and Cys5, is essential for the ability of PSD-95 to self-associate and to form cell surface clusters with Kv1.4. However, PSD-95 mutants lacking these cysteine residues retain their ability to associate with membranes and to bind to Kv1.4. Unlike wild type PSD-95, the cysteine mutant of PSD-95 cannot form a ternary complex with Kv1.4 and the cell adhesion molecule Fasciclin II. These results suggest that the N-terminal cysteines are essential for PSD-95 multimerization and that multimerization is required for simultaneous binding of multiple membrane protein ligands by PSD-95.
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synaptic clustering of the cell adhesion molecule Fasciclin II by discs large and its role in the regulation of presynaptic structure
Neuron, 1997Co-Authors: Ulrich Thomas, Morgan Sheng, Eunjoon Kim, Sven Kuhlendahl, Young Ho Koh, Eckart D Gundelfinger, Craig C Garner, Vivian BudnikAbstract:The cell adhesion molecule Fasciclin II (FASII) is involved in synapse development and plasticity. Here we provide genetic and biochemical evidence that proper localization of FASII at type I glutamatergic synapses of the Drosophila neuromuscular junction is mediated by binding between the intracellular tSXV bearing C-terminal tail of FASII and the PDZ1–2 domains of Discs-Large (DLG). Moreover, mutations in fasII and/or dlg have similar effects on presynaptic ultrastructure, suggesting their functional involvement in a common developmental pathway. DLG can directly mediate a biochemical complex and a macroscopic cluster of FASII and Shaker K+ channels in heterologous cells. These results indicate a central role for DLG in the structural organization and downstream signaling mechanisms of cell adhesion molecules and ion channels at synapses.
Corey S. Goodman - One of the best experts on this subject based on the ideXlab platform.
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homeostasis of synaptic transmission in drosophila with genetically altered nerve terminal morphology
The Journal of Neuroscience, 1996Co-Authors: Bryan A Stewart, Corey S. Goodman, Christoph M Schuster, H L AtwoodAbstract:We present a new test of the hypothesis that synaptic strength is directly related to nerve terminal morphology through analysis of synaptic transmission at Drosophila neuromuscular junctions with a genetically reduced number of nerve terminal varicosities. Synaptic transmission would decrease in target cells with fewer varicosities if there is a relationship between the number of varicosities and the strength of synaptic transmission. Animals that have an extreme hypomorphic allele of the gene for the cell adhesion molecule Fasciclin II possess fewer synapse-bearing nerve terminal varicosities; nevertheless, synaptic strength is maintained at a normal level for the muscle cell as a whole. Fewer failures of neurotransmitter release and larger excitatory junction potentials from individual varicosities, as well as more frequent spontaneous release and larger quantal units, provide evidence for enhancement of transmitter release from varicosities in the mutant. Ultrastructural analysis reveals that mutant nerve terminals have bigger synapses with more active zones per synapse, indicating that synaptic enlargement and an accompanying increase in synaptic complexity provide for more transmitter release at mutant varicosities. These results show that morphological parameters of transmitting nerve terminals can be adjusted to functionally compensate for genetic perturbations, thereby maintaining optimal synaptic transmission.
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genetic analysis of Fasciclin II in drosophila defasciculation refasciculation and altered fasciculation
Neuron, 1994Co-Authors: David M Lin, Richard D Fetter, Casey Kopczynski, Gabriele Grenningloh, Corey S. GoodmanAbstract:Abstract The Drosophila neural cell adhesion molecule Fasciclin II (Fas II) is expressed dynamically on a subset of embryonic CNS axons, many of which selectively fasciculate in the vMP2, MP1, and FN3 pathways. Here we show complementary fasll loss-of-function and gain-of-function phenotypes. Loss-of-function fasll mutations lead to the complete or partial defasciculation of all three pathways. Gain-of-function conditions, using a specific control element to direct increased levels of Fas II on the axons in these three pathways, rescue the loss-of-function phenotype. Moreover, the gain-of-function can alter fasciculation by abnormally fusing pathways together, in one case apparently by preventing normal defasciculation. These results define an in vivo function for Fas II as a neuronal recognition molecule that controls one mechanism of growth cone guidance-selective axon fasciculation-and genetically separates this function from other aspects of outgrowth and directional guidance.
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ectopic and increased expression of Fasciclin II alters motoneuron growth cone guidance
Neuron, 1994Co-Authors: David M Lin, Corey S. GoodmanAbstract:Abstract We used the enhancer detection GAL4 system in Drosophila to direct increased levels of Fasciclin II (Fas II) expression on motoneuron growth cones and axons and to direct ectopic Fas II expression on other cells they encounter. Four classes of abnormal phenotypes are, observed: "bypass" phenotypes, in which axons fail to defasciculate at the choice point where they would normally enter their muscle target region and instead extend past their target; "detour" phenotypes, in which these bypass growth cones enter their muscle target region at a different location; "stall" phenotypes, in which axons that enter their muscle target region fail to defasciculate from one another to probe their muscle targets; and "misroute" phenotypes, in which growth cones are diverted onto abnormal pathways by contact with Fas II-positive cells. These phenotypes show that changes in the pattern and level of Fas 11 expression can alter growth cone guidance, apparently in part by modulating the ability of these growth cones to respond to other guidance cues.
Goodman, Corey S. - One of the best experts on this subject based on the ideXlab platform.
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wishful thinking Encodes a BMP Type II Receptor that Regulates Synaptic Growth in Drosophila
Cell Press., 2002Co-Authors: Aberle Hermann, Fetter, Richard D., Haghighi A.pejmun, Mccabe, Brian D., Magalhães, Tiago R., Goodman, Corey S.Abstract:AbstractWe conducted a large-scale screen for Drosophila mutants that have structural abnormalities of the larval neuromuscular junction (NMJ). We recovered mutations in wishful thinking (wit), a gene that positively regulates synaptic growth. wit encodes a BMP type II receptor. In wit mutant larvae, the size of the NMJs is greatly reduced relative to the size of the muscles. wit NMJs have reduced evoked excitatory junctional potentials, decreased levels of the synaptic cell adhesion molecule Fasciclin II, and synaptic membrane detachment at active zones. Wit is expressed by a subset of neurons, including motoneurons. The NMJ phenotype is specifically rescued by transgenic expression of Wit only in motoneurons. Thus, Wit appears to function as a presynaptic receptor that regulates synaptic size at the Drosophila NMJ
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Highwire Regulates Synaptic Growth in Drosophila
Cell Press., 2000Co-Authors: Wan Hong, Fetter, Richard D., Diantonio Aaron, Bergstrom Kendra, Strauss Roland, Goodman, Corey S.Abstract:AbstractThe formation, stabilization, and growth of synaptic connections are dynamic and highly regulated processes. The glutamatergic neuromuscular junction (NMJ) in Drosophila grows new boutons and branches throughout larval development. A primary walking behavior screen followed by a secondary anatomical screen led to the identification of the highwire (hiw) gene. In hiw mutants, the specificity of motor axon pathfinding and synapse formation appears normal. However, NMJ synapses grow exuberantly and are greatly expanded in both the number of boutons and the extent and length of branches. These synapses appear normal ultrastructurally but have reduced quantal content physiologically. hiw encodes a large protein found at presynaptic terminals. Within presynaptic terminals, HIW is localized to the periactive zone surrounding active zones; Fasciclin II (Fas II), which also controls synaptic growth, is found at the same location
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Watching a Synapse Grow Noninvasive Confocal Imaging of Synaptic Growth in Drosophila
Cell Press. Published by Elsevier Inc., 1999Co-Authors: Zito Karen, Fetter, Richard D., Isacoff, Ehud Y., Parnas Dorit, Goodman, Corey S.Abstract:AbstractThe glutamatergic neuromuscular junction (NMJ) in Drosophila adds new boutons and branches during larval development. We generated transgenic fruit flies that express a novel green fluorescent membrane protein at the postsynaptic specialization, allowing for repeated noninvasive confocal imaging of synapses in live, developing larvae. As synapses grow, existing synaptic boutons stretch apart and new boutons insert between them; in addition, new boutons are added at the ends of existing strings of boutons. Some boutons are added de novo, while others bud from existing boutons. New branches form as multiple boutons bud from existing boutons. Nascent boutons contain active zones, T bars, and synaptic vesicles; we observe no specialized growth structures. Some new boutons exhibit a lower level of Fasciclin II, suggesting that the levels of this synaptic cell adhesion molecule vary locally during synaptic growth
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Genetic Analysis of the Mechanisms Controlling Target Selection: Complementary and Combinatorial Functions of Netrins, Semaphorins, and IgCAMs
Cell Press., 1998Co-Authors: Winberg, Margaret L, Mitchell, Kevin J, Goodman, Corey S.Abstract:AbstractThe molecular mechanisms controlling the ability of motor axons to recognize their appropriate muscle targets were dissected using Drosophila genetics to add or subtract Netrin A, Netrin B, Semaphorin II, and Fasciclin II alone or in combination. Fas II and Sema II are expressed by all muscles where they promote (Fas II) or inhibit (Sema II) promiscuous synaptogenesis. NetB is expressed by a subset of muscles where it attracts some axons and repels others. However, growth cones in this system apparently do not rely solely on single molecular labels on individual targets. Rather, these growth cones assess the relative balance of attractive and repulsive forces and select their targets based on the combinatorial and simultaneous input of multiple cues
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Synaptic Clustering of Fasciclin II and Shaker: Essential Targeting Sequences and Role of Dlg
Cell Press., 1997Co-Authors: Zito Karen, Fetter, Richard D., Goodman, Corey S., Isacoff, Ehud Y.Abstract:AbstractPrevious studies have shown that both the Fasciclin II (Fas II) cell adhesion molecule and the Shaker potassium channel are localized at the Drosophila neuromuscular junction, where they function in the growth and plasticity of the synapse. Here, we use the GAL4-UAS system to drive expression of the chimeric proteins CD8–Fas II and CD8–Shaker and show that the C-terminal sequences of both Fas II and Shaker are necessary and sufficient to drive the synaptic localization of a heterologous protein. Moreover, we show that the PDZ-containing protein Discs-Large (Dlg) controls the localization of these proteins, most likely through a direct interaction with their C-terminal amino acids. Finally, transient expression studies show that the pathway these proteins take to the synapse involves either an active clustering or a selective stabilization in the synaptic membrane
