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Chaya T, Maeda Y, Tsutsumi R, Ando M, Ma Y, Kajimura N, Tanaka T, Furukawa T. Ccrk-Mak/Ick signaling is a ciliary transport regulator essential for retinal photoreceptor survival. Life Sci Alliance 2024; 7:e202402880. [PMID: 39293864 PMCID: PMC11412320 DOI: 10.26508/lsa.202402880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Revised: 08/27/2024] [Accepted: 08/27/2024] [Indexed: 09/20/2024] Open
Abstract
Primary cilia are microtubule-based sensory organelles whose dysfunction causes ciliopathies in humans. The formation, function, and maintenance of primary cilia depend crucially on intraflagellar transport (IFT); however, the regulatory mechanisms of IFT at ciliary tips are poorly understood. Here, we identified that the ciliopathy kinase Mak is a ciliary tip-localized IFT regulator that cooperatively acts with the ciliopathy kinase Ick, an IFT regulator. Simultaneous disruption of Mak and Ick resulted in loss of photoreceptor ciliary axonemes and severe retinal degeneration. Gene delivery of Ick and pharmacological inhibition of FGF receptors, Ick negative regulators, ameliorated retinal degeneration in Mak -/- mice. We also identified that Ccrk kinase is an upstream activator of Mak and Ick in retinal photoreceptor cells. Furthermore, the overexpression of Mak, Ick, and Ccrk and pharmacological inhibition of FGF receptors suppressed ciliopathy-related phenotypes caused by cytoplasmic dynein inhibition in cultured cells. Collectively, our results show that the Ccrk-Mak/Ick axis is an IFT regulator essential for retinal photoreceptor maintenance and present activation of Ick as a potential therapeutic approach for retinitis pigmentosa caused by MAK mutations.
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Affiliation(s)
- Taro Chaya
- https://ror.org/035t8zc32 Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Yamato Maeda
- https://ror.org/035t8zc32 Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Ryotaro Tsutsumi
- https://ror.org/035t8zc32 Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Makoto Ando
- https://ror.org/035t8zc32 Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Yujie Ma
- https://ror.org/035t8zc32 Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Naoko Kajimura
- https://ror.org/035t8zc32 Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Osaka, Japan
| | - Teruyuki Tanaka
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takahisa Furukawa
- https://ror.org/035t8zc32 Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
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2
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Kovalevskiy O, Mateos-Garcia J, Tunyasuvunakool K. AlphaFold two years on: Validation and impact. Proc Natl Acad Sci U S A 2024; 121:e2315002121. [PMID: 39133843 PMCID: PMC11348012 DOI: 10.1073/pnas.2315002121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/29/2024] Open
Abstract
Two years on from the initial release of AlphaFold, we have seen its widespread adoption as a structure prediction tool. Here, we discuss some of the latest work based on AlphaFold, with a particular focus on its use within the structural biology community. This encompasses use cases like speeding up structure determination itself, enabling new computational studies, and building new tools and workflows. We also look at the ongoing validation of AlphaFold, as its predictions continue to be compared against large numbers of experimental structures to further delineate the model's capabilities and limitations.
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3
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Reddy Palicharla V, Mukhopadhyay S. Molecular and structural perspectives on protein trafficking to the primary cilium membrane. Biochem Soc Trans 2024; 52:1473-1487. [PMID: 38864436 PMCID: PMC11346432 DOI: 10.1042/bst20231403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/13/2024]
Abstract
The primary cilium is a dynamic subcellular compartment templated from the mother centriole or basal body. Cilia are solitary and tiny, but remarkably consequential in cellular pathways regulating proliferation, differentiation, and maintenance. Multiple transmembrane proteins such as G-protein-coupled receptors, channels, enzymes, and membrane-associated lipidated proteins are enriched in the ciliary membrane. The precise regulation of ciliary membrane content is essential for effective signal transduction and maintenance of tissue homeostasis. Surprisingly, a few conserved molecular factors, intraflagellar transport complex A and the tubby family adapter protein TULP3, mediate the transport of most membrane cargoes into cilia. Recent advances in cryogenic electron microscopy provide fundamental insights into these molecular players. Here, we review the molecular players mediating cargo delivery into the ciliary membrane through the lens of structural biology. These mechanistic insights into ciliary transport provide a framework for understanding of disease variants in ciliopathies, enable precise manipulation of cilia-mediated pathways, and provide a platform for the development of targeted therapeutics.
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Affiliation(s)
- Vivek Reddy Palicharla
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, U.S.A
| | - Saikat Mukhopadhyay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, U.S.A
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4
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Walton T, Doran MH, Brown A. Structural determination and modeling of ciliary microtubules. Acta Crystallogr D Struct Biol 2024; 80:220-231. [PMID: 38451206 PMCID: PMC10994176 DOI: 10.1107/s2059798324001815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 02/24/2024] [Indexed: 03/08/2024] Open
Abstract
The axoneme, a microtubule-based array at the center of every cilium, has been the subject of structural investigations for decades, but only recent advances in cryo-EM and cryo-ET have allowed a molecular-level interpretation of the entire complex to be achieved. The unique properties of the nine doublet microtubules and central pair of singlet microtubules that form the axoneme, including the highly decorated tubulin lattice and the docking of massive axonemal complexes, provide opportunities and challenges for sample preparation, 3D reconstruction and atomic modeling. Here, the approaches used for cryo-EM and cryo-ET of axonemes are reviewed, while highlighting the unique opportunities provided by the latest generation of AI-guided tools that are transforming structural biology.
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Affiliation(s)
- Travis Walton
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Matthew H. Doran
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Alan Brown
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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5
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Rao L, Gennerich A. Structure and Function of Dynein's Non-Catalytic Subunits. Cells 2024; 13:330. [PMID: 38391943 PMCID: PMC10886578 DOI: 10.3390/cells13040330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/05/2024] [Accepted: 02/09/2024] [Indexed: 02/24/2024] Open
Abstract
Dynein, an ancient microtubule-based motor protein, performs diverse cellular functions in nearly all eukaryotic cells, with the exception of land plants. It has evolved into three subfamilies-cytoplasmic dynein-1, cytoplasmic dynein-2, and axonemal dyneins-each differentiated by their cellular functions. These megadalton complexes consist of multiple subunits, with the heavy chain being the largest subunit that generates motion and force along microtubules by converting the chemical energy of ATP hydrolysis into mechanical work. Beyond this catalytic core, the functionality of dynein is significantly enhanced by numerous non-catalytic subunits. These subunits are integral to the complex, contributing to its stability, regulating its enzymatic activities, targeting it to specific cellular locations, and mediating its interactions with other cofactors. The diversity of non-catalytic subunits expands dynein's cellular roles, enabling it to perform critical tasks despite the conservation of its heavy chains. In this review, we discuss recent findings and insights regarding these non-catalytic subunits.
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Affiliation(s)
- Lu Rao
- Department of Biochemistry and Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Arne Gennerich
- Department of Biochemistry and Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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6
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McCafferty CL, Klumpe S, Amaro RE, Kukulski W, Collinson L, Engel BD. Integrating cellular electron microscopy with multimodal data to explore biology across space and time. Cell 2024; 187:563-584. [PMID: 38306982 DOI: 10.1016/j.cell.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/03/2024] [Accepted: 01/03/2024] [Indexed: 02/04/2024]
Abstract
Biology spans a continuum of length and time scales. Individual experimental methods only glimpse discrete pieces of this spectrum but can be combined to construct a more holistic view. In this Review, we detail the latest advancements in volume electron microscopy (vEM) and cryo-electron tomography (cryo-ET), which together can visualize biological complexity across scales from the organization of cells in large tissues to the molecular details inside native cellular environments. In addition, we discuss emerging methodologies for integrating three-dimensional electron microscopy (3DEM) imaging with multimodal data, including fluorescence microscopy, mass spectrometry, single-particle analysis, and AI-based structure prediction. This multifaceted approach fills gaps in the biological continuum, providing functional context, spatial organization, molecular identity, and native interactions. We conclude with a perspective on incorporating diverse data into computational simulations that further bridge and extend length scales while integrating the dimension of time.
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Affiliation(s)
| | - Sven Klumpe
- Research Group CryoEM Technology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
| | - Rommie E Amaro
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Wanda Kukulski
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
| | - Lucy Collinson
- Electron Microscopy Science Technology Platform, Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
| | - Benjamin D Engel
- Biozentrum, University of Basel, Spitalstrasse 41, 4056 Basel, Switzerland.
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Moran AL, Louzao-Martinez L, Norris DP, Peters DJM, Blacque OE. Transport and barrier mechanisms that regulate ciliary compartmentalization and ciliopathies. Nat Rev Nephrol 2024; 20:83-100. [PMID: 37872350 DOI: 10.1038/s41581-023-00773-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2023] [Indexed: 10/25/2023]
Abstract
Primary cilia act as cell surface antennae, coordinating cellular responses to sensory inputs and signalling molecules that regulate developmental and homeostatic pathways. Cilia are therefore critical to physiological processes, and defects in ciliary components are associated with a large group of inherited pleiotropic disorders - known collectively as ciliopathies - that have a broad spectrum of phenotypes and affect many or most tissues, including the kidney. A central feature of the cilium is its compartmentalized structure, which imparts its unique molecular composition and signalling environment despite its membrane and cytosol being contiguous with those of the cell. Such compartmentalization is achieved via active transport pathways that bring protein cargoes to and from the cilium, as well as gating pathways at the ciliary base that establish diffusion barriers to protein exchange into and out of the organelle. Many ciliopathy-linked proteins, including those involved in kidney development and homeostasis, are components of the compartmentalizing machinery. New insights into the major compartmentalizing pathways at the cilium, namely, ciliary gating, intraflagellar transport, lipidated protein flagellar transport and ciliary extracellular vesicle release pathways, have improved our understanding of the mechanisms that underpin ciliary disease and associated renal disorders.
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Affiliation(s)
- Ailis L Moran
- School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Laura Louzao-Martinez
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Dorien J M Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
| | - Oliver E Blacque
- School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.
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8
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Udupa P, Ghosh DK. The emerging functions of intraflagellar transport 52 in ciliary transport and ciliopathies. Traffic 2024; 25:e12929. [PMID: 38272449 DOI: 10.1111/tra.12929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/31/2023] [Accepted: 12/26/2023] [Indexed: 01/27/2024]
Abstract
Ciliary transport in eukaryotic cells is an intricate and conserved process involving the coordinated assembly and functioning of a multiprotein intraflagellar transport (IFT) complex. Among the various IFT proteins, intraflagellar transport 52 (IFT52) plays a crucial role in ciliary transport and is implicated in various ciliopathies. IFT52 is a core component of the IFT-B complex that facilitates movement of cargoes along the ciliary axoneme. Stable binding of the IFT-B1 and IFT-B2 subcomplexes by IFT52 in the IFT-B complex regulates recycling of ciliary components and maintenance of ciliary functions such as signal transduction and molecular movement. Mutations in the IFT52 gene can disrupt ciliary trafficking, resulting in dysfunctional cilia and affecting cellular processes in ciliopathies. Such ciliopathies caused by IFT52 mutations exhibit a wide range of clinical features, including skeletal developmental abnormalities, retinal degeneration, respiratory failure and neurological abnormalities in affected individuals. Therefore, IFT52 serves as a promising biomarker for the diagnosis of various ciliopathies, including short-rib thoracic dysplasia 16 with or without polydactyly. Here, we provide an overview of the IFT52-mediated molecular mechanisms underlying ciliary transport and describe the IFT52 mutations that cause different disorders associated with cilia dysfunction.
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Affiliation(s)
- Prajna Udupa
- Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Debasish Kumar Ghosh
- Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
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Gonçalves-Santos F, De-Castro ARG, Rodrigues DRM, De-Castro MJG, Gassmann R, Abreu CMC, Dantas TJ. Hot-wiring dynein-2 establishes roles for IFT-A in retrograde train assembly and motility. Cell Rep 2023; 42:113337. [PMID: 37883232 DOI: 10.1016/j.celrep.2023.113337] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/08/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023] Open
Abstract
Intraflagellar transport (IFT) trains, built around IFT-A and IFT-B complexes, are carried by opposing motors to import and export ciliary cargo. While transported by kinesin-2 on anterograde IFT trains, the dynein-2 motor adopts an autoinhibitory conformation until it needs to be activated at the ciliary tip to power retrograde IFT. Growing evidence has linked the IFT-A complex to retrograde IFT; however, its roles in this process remain unknown. Here, we use CRISPR-Cas9-mediated genome editing to disable the dynein-2 autoinhibition mechanism in Caenorhabditis elegans and assess its impact on IFT with high-resolution live imaging and photobleaching analyses. Remarkably, this dynein-2 "hot-wiring" approach reignites retrograde motility inside IFT-A-deficient cilia without triggering tug-of-war events. In addition to providing functional evidence that multiple mechanisms maintain dynein-2 inhibited during anterograde IFT, our data establish key roles for IFT-A in mediating motor-train coupling during IFT turnaround, promoting retrograde IFT initiation, and modulating dynein-2 retrograde motility.
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Affiliation(s)
- Francisco Gonçalves-Santos
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Ana R G De-Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Diogo R M Rodrigues
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria J G De-Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Reto Gassmann
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Carla M C Abreu
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
| | - Tiago J Dantas
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
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Tasaki K, Zhou Z, Ishida Y, Katoh Y, Nakayama K. Compound heterozygous IFT81 variations in a skeletal ciliopathy patient cause Bardet-Biedl syndrome-like ciliary defects. Hum Mol Genet 2023; 32:2887-2900. [PMID: 37427975 DOI: 10.1093/hmg/ddad112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/04/2023] [Accepted: 07/04/2023] [Indexed: 07/11/2023] Open
Abstract
Owing to their crucial roles in development and homeostasis, defects in cilia cause ciliopathies with diverse clinical manifestations. The intraflagellar transport (IFT) machinery, containing the IFT-A and IFT-B complexes, mediates not only the intraciliary bidirectional trafficking but also import and export of ciliary proteins together with the kinesin-2 and dynein-2 motor complexes. The BBSome, containing eight subunits encoded by causative genes of Bardet-Biedl syndrome (BBS), connects the IFT machinery to ciliary membrane proteins to mediate their export from cilia. Although mutations in subunits of the IFT-A and dynein-2 complexes cause skeletal ciliopathies, mutations in some IFT-B subunits are also known to cause skeletal ciliopathies. We here show that compound heterozygous variations of an IFT-B subunit, IFT81, found in a patient with skeletal ciliopathy cause defects in its interactions with other IFT-B subunits, and in ciliogenesis and ciliary protein trafficking when one of the two variants was expressed in IFT81-knockout (KO) cells. Notably, we found that IFT81-KO cells expressing IFT81(Δ490-519), which lacks the binding site for the IFT25-IFT27 dimer, causes ciliary defects reminiscent of those found in BBS cells and those in IFT74-KO cells expressing a BBS variant of IFT74, which forms a heterodimer with IFT81. In addition, IFT81-KO cells expressing IFT81(Δ490-519) in combination with the other variant, IFT81 (L645*), which mimics the cellular conditions of the above skeletal ciliopathy patient, demonstrated essentially the same phenotype as those expressing only IFT81(Δ490-519). Thus, our data indicate that BBS-like defects can be caused by skeletal ciliopathy variants of IFT81.
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Affiliation(s)
- Koshi Tasaki
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Zhuang Zhou
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Yamato Ishida
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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11
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Ishikawa T. Architecture of intraflagellar transport complexes. Nat Struct Mol Biol 2023; 30:570-573. [PMID: 37198269 DOI: 10.1038/s41594-023-00986-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Affiliation(s)
- Takashi Ishikawa
- Department of Biology and Chemistry, Paul Scherrer Institute Villigen, Villigen, Switzerland.
- Department of Biology, ETH Zurich, Zurich, Switzerland.
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