The Experts below are selected from a list of 3492 Experts worldwide ranked by ideXlab platform
Trina A Schroer - One of the best experts on this subject based on the ideXlab platform.
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cryo electron tomography reveals that Dynactin recruits a team of dyneins for processive motility
Nature Structural & Molecular Biology, 2018Co-Authors: Danielle A. Grotjahn, Trina A Schroer, Saikat Chowdhury, Richard J. Mckenney, Gabriel C. LanderAbstract:Cytoplasmic dynein is a protein complex that transports molecular cargo along microtubules (MTs), playing a key role in the intracellular trafficking network. Vertebrate dynein’s movement becomes strikingly enhanced upon interacting with Dynactin and a cargo adaptor such as BicaudalD2. However, the mechanisms responsible for increased transport activity are not well understood, largely owing to limited structural information. We used cryo-electron tomography (cryo-ET) to visualize the 3D structure of the MT-bound dynein–Dynactin complex from Mus musculus and show that the Dynactin–cargo adaptor complex binds two dimeric dyneins. This configuration imposes spatial and conformational constraints on both dynein dimers, positioning the four motor domains in proximity to one another and oriented toward the MT minus end. We propose that grouping multiple dyneins onto a single Dynactin scaffold promotes collective force production, increased processivity, and unidirectional movement, suggesting mechanistic parallels to axonemal dynein. These findings provide structural insights into a previously unknown mechanism for dynein regulation.
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Cryo-electron tomography reveals that Dynactin recruits a team of dyneins for processive motility
2017Co-Authors: Danielle A. Grotjahn, Trina A Schroer, Saikat Chowdhury, Richard J. Mckenney, Gabriel C. LanderAbstract:A key player in the intracellular trafficking network is cytoplasmic dynein, a protein complex that transports molecular cargo along microtubule tracks. It has been shown that vertebrate dynein9s movement becomes strikingly enhanced upon interacting with a cofactor named Dynactin and one of several cargo-adapters, such as BicaudalD2. However, the mechanisms responsible for this increase in transport efficiency are not well understood, largely due to a lack of structural information. We used cryo-electron tomography to visualize the first 3-dimensional structure of the intact dynein-Dynactin complex bound to microtubules. Our structure reveals that the Dynactin-cargo-adapter complex recruits and binds to two dimeric cytoplasmic dyneins. Interestingly, the dynein motor organization closely resembles that of axonemal dynein, suggesting that cytoplasmic dynein and axonemal dyneins may utilize similar mechanisms to coordinate multiple motors. We propose that grouping dyneins onto a single Dynactin scaffold promotes collective force production as well as unidirectional processive motility. These findings provide a structural platform that facilitates a deeper biochemical and biophysical understanding of dynein regulation and cellular transport.
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Mycalolide B dissociates Dynactin and abolishes retrograde axonal transport of dense-core vesicles
Molecular biology of the cell, 2015Co-Authors: Samantha L. Cavolo, Trina A Schroer, Stephanie A. Ketcham, Chaoming Zhou, Matthew M. Suzuki, Kresimir Ukalovic, Michael A. Silverman, Edwin S. LevitanAbstract:Axonal transport is critical for maintaining synaptic transmission. Of interest, anterograde and retrograde axonal transport appear to be interdependent, as perturbing one directional motor often impairs movement in the opposite direction. Here live imaging of Drosophila and hippocampal neuron dense-core vesicles (DCVs) containing a neuropeptide or brain-derived neurotrophic factor shows that the F-actin depolymerizing macrolide toxin mycalolide B (MB) rapidly and selectively abolishes retrograde, but not anterograde, transport in the axon and the nerve terminal. Latrunculin A does not mimic MB, demonstrating that F-actin depolymerization is not responsible for unidirectional transport inhibition. Given that Dynactin initiates retrograde transport and that amino acid sequences implicated in macrolide toxin binding are found in the Dynactin component actin-related protein 1, we examined Dynactin integrity. Remarkably, cell extract and purified protein experiments show that MB induces disassembly of the Dynactin complex. Thus imaging selective retrograde transport inhibition led to the discovery of a small-molecule Dynactin disruptor. The rapid unidirectional inhibition by MB suggests that Dynactin is absolutely required for retrograde DCV transport but does not directly facilitate ongoing anterograde DCV transport in the axon or nerve terminal. More generally, MB's effects bolster the conclusion that anterograde and retrograde axonal transport are not necessarily interdependent.
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Dynactin integrity depends upon direct binding of dynamitin to Arp1
Molecular biology of the cell, 2014Co-Authors: Frances Ka Yan Cheong, John R. Yates, Lijuan Feng, Ali Sarkeshik, Trina A SchroerAbstract:Dynactin is a multiprotein complex that works with cytoplasmic dynein and other motors to support a wide range of cell functions. It serves as an adaptor that binds both dynein and cargoes and enhances single-motor processivity. The Dynactin subunit dynamitin (also known as p50) is believed to be integral to Dynactin structure because free dynamitin displaces the dynein-binding p150Glued subunit from the cargo-binding Arp1 filament. We show here that the intrinsically disordered dynamitin N-terminus binds to Arp1 directly. When expressed in cells, dynamitin amino acids (AA) 1–87 causes complete release of endogenous dynamitin, p150, and p24 from Dynactin, leaving behind Arp1 filaments carrying the remaining Dynactin subunits (CapZ, p62, Arp11, p27, and p25). Tandem-affinity purification–tagged dynamitin AA 1–87 binds the Arp filament specifically, and binding studies with purified native Arp1 reveal that this fragment binds Arp1 directly. Neither CapZ nor the p27/p25 dimer contributes to interactions between dynamitin and the Arp filament. This work demonstrates for the first time that Arp1 can directly bind any protein besides another Arp and provides important new insight into the underpinnings of Dynactin structure.
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nudel nude and lis1 promote dynein and Dynactin interaction in the context of spindle morphogenesis
Molecular Biology of the Cell, 2013Co-Authors: Shusheng Wang, Trina A Schroer, Stephanie A. Ketcham, Arne Schön, Benjamin Goodman, Yueju Wang, John R. Yates, Ernesto Freire, Yixian ZhengAbstract:Lis1, Nudel/NudE, and Dynactin are regulators of cytoplasmic dynein, a minus end–directed, microtubule (MT)-based motor required for proper spindle assembly and orientation. In vitro studies have shown that Dynactin promotes processive movement of dynein on MTs, whereas Lis1 causes dynein to enter a persistent force-generating state (referred to here as dynein stall). Yet how the activities of Lis1, Nudel/NudE, and Dynactin are coordinated to regulate dynein remains poorly understood in vivo. Working in Xenopus egg extracts, we show that Nudel/NudE facilitates the binding of Lis1 to dynein, which enhances the recruitment of Dynactin to dynein. We further report a novel Lis1-dependent dynein–Dynactin interaction that is essential for the organization of mitotic spindle poles. Finally, using assays for MT gliding and spindle assembly, we demonstrate an antagonistic relationship between Lis1 and Dynactin that allows Dynactin to relieve Lis1-induced dynein stall on MTs. Our findings suggest the interesting possibility that Lis1 and Dynactin could alternately engage with dynein to allow the motor to promote spindle assembly.
Erika L F Holzbaur - One of the best experts on this subject based on the ideXlab platform.
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a conserved interaction of the dynein light intermediate chain with dynein Dynactin effectors necessary for processivity
Nature Communications, 2018Co-Authors: Ingyun Lee, Erika L F Holzbaur, Mara A. Olenick, Malgorzata Boczkowska, Clara Franziniarmstrong, Roberto DominguezAbstract:Cytoplasmic dynein is the major minus-end-directed microtubule-based motor in cells. Dynein processivity and cargo selectivity depend on cargo-specific effectors that, while generally unrelated, share the ability to interact with dynein and Dynactin to form processive dynein-Dynactin-effector complexes. How this is achieved is poorly understood. Here, we identify a conserved region of the dynein Light Intermediate Chain 1 (LIC1) that mediates interactions with unrelated dynein-Dynactin effectors. Quantitative binding studies map these interactions to a conserved helix within LIC1 and to N-terminal fragments of Hook1, Hook3, BICD2, and Spindly. A structure of the LIC1 helix bound to the N-terminal Hook domain reveals a conformational change that creates a hydrophobic cleft for binding of the LIC1 helix. The LIC1 helix competitively inhibits processive dynein-Dynactin-effector motility in vitro, whereas structure-inspired mutations in this helix impair lysosomal positioning in cells. The results reveal a conserved mechanism of effector interaction with dynein-Dynactin necessary for processive motility.
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A conserved interaction of the dynein light intermediate chain with dynein-Dynactin effectors necessary for processivity
Nature Publishing Group, 2018Co-Authors: Ingyun Lee, Erika L F Holzbaur, Mara A. Olenick, Malgorzata Boczkowska, Clara Franzini-armstrong, Roberto DominguezAbstract:A growing number of cargo-specific effector proteins are being identified that interact with both dynein and Dynactin and form processive dynein-Dynactin-effector complexes. Here the authors identify and characterize a conserved mechanism of interaction between dynein and unrelated effector proteins
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Dynactin functions as both a dynamic tether and brake during dynein-driven motility
Nature communications, 2014Co-Authors: Swathi Ayloo, Mariko Tokito, Jacob E. Lazarus, Aditya Dodda, E Michael Ostap, Erika L F HolzbaurAbstract:It remains unclear how the Dynactin complex activates cytoplasmic dynein motor proteins. Ayloo et al. use single molecule imaging to observe dynein–Dynactin behaviour on microtubules, and show that Dynactin recruits dynein to microtubules and acts as a brake to slow the motor.
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Dynactin Is Required for Transport Initiation From the Distal Axon
Neuron, 2012Co-Authors: Armen J. Moughamian, Erika L F HolzbaurAbstract:Dynactin is a required cofactor for the minus-end-directed microtubule motor cytoplasmic dynein. Mutations within the highly conserved CAP-Gly domain of Dynactin cause neurodegenerative disease. Here, we show that the CAP-Gly domain is necessary to enrich Dynactin at the distal end of primary neurons. While the CAP-Gly domain is not required for sustained transport along the axon, we find that the distal accumulation facilitates the efficient initiation of retrograde vesicular transport from the neurite tip. Neurodegenerative disease mutations in the CAP-Gly domain prevent the distal enrichment of Dynactin thereby inhibiting the initiation of retrograde transport. Thus, we propose a model in which distal Dynactin is a key mediator in promoting the interaction among the microtubule, dynein motor, and cargo for the efficient initiation of transport. Mutations in the CAP-Gly domain disrupt the formation of the motor-cargo complex, highlighting the specific defects in axonal transport that may lead to neurodegeneration.
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Regulation of Dynactin through the Differential Expression of p150Glued Isoforms
The Journal of biological chemistry, 2008Co-Authors: Ram Dixit, Mariko Tokito, Lee A Ligon, Jennifer R. Levy, Erika L F HolzbaurAbstract:Cytoplasmic dynein and Dynactin interact to drive microtubule-based transport in the cell. The p150Glued subunit of Dynactin binds to dynein, and directly to microtubules. We have identified alternatively spliced isoforms of p150Glued that are expressed in a tissue-specific manner and which differ significantly in their affinity for microtubules. Live cell assays indicate that these alternatively spliced isoforms also differ significantly in their microtubule plus end-tracking activity, suggesting a mechanism by which the cell may regulate the dynamic localization of Dynactin. To test the function of the microtubule-binding domain of p150Glued, we used RNAi to deplete the endogenous polypeptide from HeLa cells, followed by rescue with constructs encoding either the full-length polypeptide or an isoform lacking the microtubule-binding domain. Both constructs fully rescued defects in Golgi morphology induced by depletion of p150Glued, indicating that an independent microtubule-binding site in Dynactin may not be required for Dynactin-mediated trafficking in some mammalian cell types. In neurons, however, a mutation within the microtubule-binding domain of p150Glued results in motor neuron disease; here we investigate the effects of four other mutations in highly conserved domains of the polypeptide (M571T, R785W, R1101K, and T1249I) associated in genetic studies with Amyotrophic Lateral Sclerosis. Both biochemical and cellular assays reveal that these amino acid substitutions do not result in functional differences, suggesting that these sequence changes are either allelic variants or contributory risk factors rather than causative for motor neuron disease. Together, these studies provide further insight into the regulation of dynein-Dynactin function in the cell.
Ronald D Vale - One of the best experts on this subject based on the ideXlab platform.
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assembly and activation of dynein Dynactin by the cargo adaptor protein hook3
Journal of Cell Biology, 2016Co-Authors: Courtney M Schroeder, Ronald D ValeAbstract:Metazoan cytoplasmic dynein moves processively along microtubules with the aid of Dynactin and an adaptor protein that joins dynein and Dynactin into a stable ternary complex. Here, we examined how Hook3, a cargo adaptor involved in Golgi and endosome transport, forms a motile dynein-Dynactin complex. We show that the conserved Hook domain interacts directly with the dynein light intermediate chain 1 (LIC1). By solving the crystal structure of the Hook domain and using structure-based mutagenesis, we identify two conserved surface residues that are each critical for LIC1 binding. Hook proteins with mutations in these residues fail to form a stable dynein-Dynactin complex, revealing a crucial role for LIC1 in this interaction. We also identify a region of Hook3 specifically required for an allosteric activation of processive motility. Our work reveals the structural details of Hook3's interaction with dynein and offers insight into how cargo adaptors form processive dynein-Dynactin motor complexes.
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assembly and activation of dynein Dynactin by the cargo adaptor protein hook3
bioRxiv, 2016Co-Authors: Courtney M Schroeder, Ronald D ValeAbstract:Metazoan cytoplasmic dynein moves processively along microtubules with the aid of Dynactin and an adaptor protein that joins dynein and Dynactin into a stable ternary complex. Here, we have examined how Hook3, a cargo adaptor involved in Golgi and endosome transport, forms a motile dynein-Dynactin complex. We show that the conserved Hook domain interacts directly with the dynein light intermediate chain 1 (LIC1). By solving the crystal structure of the Hook domain and using structure-based mutagenesis, we identify two conserved surface residues that are each critical for LIC1 binding. Hook proteins with mutations in these residues fail to form a stable dynein-Dynactin complex, revealing a crucial role for LIC1 in this interaction. We also identify a region of Hook3 specifically required for an allosteric activation of processive motility. Our work reveals the structural details of Hook3's interaction with dynein and offers insight into how cargo adaptors form processive dynein-Dynactin motor complexes.
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Activation of cytoplasmic dynein motility by Dynactin-cargo adapter complexes
Science, 2014Co-Authors: R. J. Mckenney, Walter Huynh, Gira Bhabha, Marvin E. Tanenbaum, Ronald D ValeAbstract:Cytoplasmic dynein is a molecular motor that transports a large variety of cargoes (e.g., organelles, messenger RNAs, and viruses) along microtubules over long intracellular distances. The Dynactin protein complex is important for dynein activity in vivo, but its precise role has been unclear. Here, we found that purified mammalian dynein did not move processively on microtubules in vitro. However, when dynein formed a complex with Dynactin and one of four different cargo-specific adapter proteins, the motor became ultraprocessive, moving for distances similar to those of native cargoes in living cells. Thus, we propose that dynein is largely inactive in the cytoplasm and that a variety of adapter proteins activate processive motility by linking Dynactin to dynein only when the motor is bound to its proper cargo.
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regulation of the processivity and intracellular localization of saccharomyces cerevisiae dynein by Dynactin
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Julia R Kardon, Samara L Reckpeterson, Ronald D ValeAbstract:Dynactin, a large multisubunit complex, is required for intracellular transport by dynein; however, its cellular functions and mechanism of action are not clear. Prior studies suggested that Dynactin increases dynein processivity by tethering the motor to the microtubule through its own microtubule binding domains. However, this hypothesis could not be tested without a recombinant source of Dynactin. Here, we have produced recombinant Dynactin and dynein in Saccharomyces cerevisiae, and examined the effect of Dynactin on dynein in single-molecule motility assays. We show that Dynactin increases the run length of single dynein motors, but does not alter the directionality of dynein movement. Enhancement of dynein processivity by Dynactin does not require the microtubule (MT) binding domains of Nip100 (the yeast p150Glued homolog). Dynactin lacking these MT binding domains also supports the proper localization and function of dynein during nuclear segregation in vivo. Instead, a segment of the coiled-coil of Nip100 is required for these activities. Our results directly demonstrate that Dynactin increases the processivity of dynein through a mechanism independent of microtubule tethering.
Andrew P Carter - One of the best experts on this subject based on the ideXlab platform.
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Cryo-EM shows how Dynactin recruits two dyneins for faster movement
Nature, 2018Co-Authors: L Urnavicius, Mohamed M. Elshenawy, Carina Motz, Ahmet Yildiz, Clinton K. Lau, Edgar Morales-rios, Andrew P CarterAbstract:Dynein and its cofactor Dynactin form a highly processive microtubule motor in the presence of an activating adaptor, such as BICD2. Different adaptors link dynein and Dynactin to distinct cargoes. Here we use electron microscopy and single-molecule studies to show that adaptors can recruit a second dynein to Dynactin. Whereas BICD2 is biased towards recruiting a single dynein, the adaptors BICDR1 and HOOK3 predominantly recruit two dyneins. We find that the shift towards a double dynein complex increases both the force and speed of the microtubule motor. Our 3.5 Å resolution cryo-electron microscopy reconstruction of a dynein tail–Dynactin–BICDR1 complex reveals how Dynactin can act as a scaffold to coordinate two dyneins side-by-side. Our work provides a structural basis for understanding how diverse adaptors recruit different numbers of dyneins and regulate the motile properties of the dynein–Dynactin transport machine. In eukaryotic cells, the cytoplasmic protein dynein-1 (dynein) is the main transporter of cargoes towards the minus ends of microtubules—tube-like components of the cytoskeleton that, together with motor proteins, move material within the cell. Dynein is converted into a highly processive motor protein through binding both to its cofactor Dynactin and to a cargo adaptor, such as BICD2, BICDR1 or HOOK3. BICD2 preferentially binds to one molecule of dynein and one molecule of Dynactin. Using cryo-electron microscopy Andrew Carter and team show that, in contrast, BICDR1 and HOOK3 bind to a complex of two dyneins, which are brought together by a Dynactin scaffold. The authors' single-molecule studies highlight that this configuration increases both the force and speed of the motor complex. Cryo-electron microscopy and single-molecule studies reveal that the adaptors BICDR1 and HOOK3 recruit two dynein molecules to Dynactin and thereby increase the force and speed of the dynein–Dynactin microtubule motor.
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Cryo-EM shows how Dynactin recruits two dyneins for faster movement
2017Co-Authors: L Urnavicius, Mohamed M. Elshenawy, Carina Motz, Ahmet Yildiz, Clinton K. Lau, Edgar Morales-rios, Andrew P CarterAbstract:Dynein and its cofactor Dynactin form a highly processive microtubule motor in the presence of an activating adaptor, such as BICD2. Different adaptors link dynein/Dynactin to distinct cargos. Here we use electron microscopy (EM) and single molecule studies to show that adaptors can recruit a second dynein to Dynactin. Whereas BICD2 is biased toward recruiting a single dynein, the adaptors BICDR1 and HOOK3 predominantly recruit two. We find that the shift toward a double dynein complex increases both force and speed. A 3.5 A cryo-EM reconstruction of a dynein tail/Dynactin/BICDR1 complex reveals how Dynactin can act as a scaffold to coordinate two dyneins side by side. Our work provides a structural basis for how diverse adaptors recruit different numbers of dyneins and regulate the motile properties of the dynein/Dynactin transport machine.
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cryo em reveals how human cytoplasmic dynein is auto inhibited and activated
Cell, 2017Co-Authors: Kai Zhang, Helen Foster, Arnaud Rondelet, Samuel E Lacey, Nadia Bahibuisson, Alexander W Bird, Andrew P CarterAbstract:Cytoplasmic dynein-1 binds Dynactin and cargo adaptor proteins to form a transport machine capable of long-distance processive movement along microtubules. However, it is unclear why dynein-1 moves poorly on its own or how it is activated by Dynactin. Here, we present a cryoelectron microscopy structure of the complete 1.4-megadalton human dynein-1 complex in an inhibited state known as the phi-particle. We reveal the 3D structure of the cargo binding dynein tail and show how self-dimerization of the motor domains locks them in a conformation with low microtubule affinity. Disrupting motor dimerization with structure-based mutagenesis drives dynein-1 into an open form with higher affinity for both microtubules and Dynactin. We find the open form is also inhibited for movement and that Dynactin relieves this by reorienting the motor domains to interact correctly with microtubules. Our model explains how Dynactin binding to the dynein-1 tail directly stimulates its motor activity.
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How dynein and Dynactin transport cargos: a structural perspective
Current opinion in structural biology, 2016Co-Authors: Andrew P Carter, A G Diamant, L UrnaviciusAbstract:Recent structures of the dynein motor in three different conformations reveal how it uses ATP hydrolysis to move along microtubules. Attention is now turning to how cytoplasmic dynein-1 and Dynactin act together to carry cargos. Cryo-electron microscopy (cryo-EM) has revealed the structure of Dynactin and how it binds dynein in the presence of a cargo adaptor protein Bicaudal-D2 (BICD2). Future questions will include how dynein-1 transports so many different cargos and how the 2.4MDa dynein/Dynactin transport machine is regulated.
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the structure of the Dynactin complex and its interaction with dynein
Science, 2015Co-Authors: L Urnavicius, A G Diamant, Carina Motz, Minmin Yu, Nisha A Patel, Carol V. Robinson, Max A Schlager, Andrew P CarterAbstract:Dynactin is an essential cofactor of the microtubule motor, cytoplasmic dynein. Dynactin contains 23 subunits built around a short filament of an actin-related protein (Arp1). How Dynactin is assembled, how it functions with dynein, and why it is built around an actin-like filament is unclear. Urnavicius et al. combined cryo–electron microscopy structural studies and a crystal structure to determine the three-dimensional architecture of Dynactin and how it interacts with dynein. Science , this issue p. [1441][1] [1]: /lookup/doi/10.1126/science.aaa4080
Steven R Gill - One of the best experts on this subject based on the ideXlab platform.
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analysis of Dynactin subcomplexes reveals a novel actin related protein associated with the arp1 minifilament pointed end
Journal of Cell Biology, 1999Co-Authors: Mark D Eckley, James B Bingham, Karin A Melkonian, Steven R Gill, John E Heuser, Holly V. Goodson, Trina A SchroerAbstract:The multisubunit protein, Dynactin, is a critical component of the cytoplasmic dynein motor machinery. Dynactin contains two distinct structural domains: a projecting sidearm that interacts with dynein and an actin-like minifilament backbone that is thought to bind cargo. Here, we use biochemical, ultrastructural, and molecular cloning techniques to obtain a comprehensive picture of Dynactin composition and structure. Treatment of purified Dynactin with recombinant dynamitin yields two assemblies: the actin-related protein, Arp1, minifilament and the p150 Glued sidearm. Both contain dynamitin. Treatment of Dynactin with the chaotropic salt, potassium iodide, completely depolymerizes the Arp1 minifilament to reveal multiple protein complexes that contain the remaining Dynactin subunits. The shoulder/sidearm complex contains p150 Glued , dynamitin, and p24 subunits and is ultrastructurally similar to Dynactin9s flexible projecting sidearm. The Dynactin shoulder complex, which contains dynamitin and p24, is an elongated, flexible assembly that may link the shoulder/sidearm complex to the Arp1 minifilament. Pointed-end complex contains p62, p27, and p25 subunits, plus a novel actin-related protein, Arp11. p62, p27, and p25 contain predicted cargo-binding motifs, while the Arp11 sequence suggests a pointed-end capping activity. These isolated Dynactin subdomains will be useful tools for further analysis of Dynactin assembly and function.
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Dynactin is required for microtubule anchoring at centrosomes
Journal of Cell Biology, 1999Co-Authors: Nicholas J Quintyne, Steven R Gill, D M Eckley, C L Crego, Duane A Compton, Trina A SchroerAbstract:The multiprotein complex, Dynactin, is an integral part of the cytoplasmic dynein motor and is required for dynein-based motility in vitro and in vivo. In living cells, perturbation of the dynein–Dynactin interaction profoundly blocks mitotic spindle assembly, and inhibition or depletion of dynein or Dynactin from meiotic or mitotic cell extracts prevents microtubules from focusing into spindles. In interphase cells, perturbation of the dynein–Dynactin complex is correlated with an inhibition of ER-to-Golgi movement and reorganization of the Golgi apparatus and the endosome–lysosome system, but the effects on microtubule organization have not previously been defined. To explore this question, we overexpressed a variety of Dynactin subunits in cultured fibroblasts. Subunits implicated in dynein binding have effects on both microtubule organization and centrosome integrity. Microtubules are reorganized into unfocused arrays. The pericentriolar components, γ tubulin and Dynactin, are lost from centrosomes, but pericentrin localization persists. Microtubule nucleation from centrosomes proceeds relatively normally, but microtubules become disorganized soon thereafter. Overexpression of some, but not all, Dynactin subunits also affects endomembrane localization. These data indicate that dynein and Dynactin play important roles in microtubule organization at centrosomes in fibroblastic cells and provide new insights into Dynactin–cargo interactions.
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actin related protein 1 and cytoplasmic dynein based motility what s the connection
Trends in Cell Biology, 1996Co-Authors: Trina A Schroer, James B Bingham, Steven R GillAbstract:Abstract The actin-related protein Arp1 works in conjunction with the microtubule-based motor cytoplasmic dynein to drive many types of intracellular motility. In vertebrate cells, Arp1 is present exclusively in the form of a 37-nm filament that constitutes the backbone of Dynactin, a 1.2-MDa macromolecular complex containing nine other polypeptides. Dynactin has been proposed to function as the link between dynein and its cargo. Recent work indicates that the Dynactin subunit p150 Glued mediates the interaction of the Dynactin molecule with dynein and microtubules, leaving the Arp1 filament as a possible cargo-binding domain. Mechanisms for binding of F-actin to membranes are discussed as models of the Arp1-membrane interaction.
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ultrastructural analysis of the Dynactin complex an actin related protein is a component of a filament that resembles f actin
Journal of Cell Biology, 1994Co-Authors: Dorothy A Schafer, Steven R Gill, John E Heuser, John A. Cooper, Trina A SchroerAbstract:The Dynactin complex visualized by deepetch electron microscopy appears as a short filament 37-nm in length, which resembles F-actin, plus a thinner, laterally oriented filament that terminates in two globular heads. The locations of several of the constituent polypeptides were identified on this structure by applying antibodies to decorate the Dynactin complex before processing for electron microscopy. Antibodies to the actin-related protein Arp1 (previously referred to as actin-RPV), bound at various sites along the filament, demonstrating that this protein assembles in a polymer similar to conventional actin. Antibodies to the barbed-end actin-binding protein, capping protein, bound to one end of the filament. Thus, an actin-binding protein that binds conventional actin may also bind to Arp1 to regulate its polymerization. Antibodies to the 62-kD component of the Dynactin complex also bound to one end of the filament. An antibody that binds the COOH-terminal region of the 160/150-kD Dynactin polypeptides bound to the globular domains at the end of the thin lateral filament, suggesting that the Dynactin polypeptide comprises at least part of the sidearm structure.
