Cytoskeletal Elements
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
The Desmoplakin Carboxyl Terminus Coaligns with and Specifically Disrupts Intermediate Filament Networks When Expressed in Cultured Cells Thaddeus S
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PubMed Central The Desmoplakin Carboxyl Terminus Coaligns with and Specifically Disrupts Intermediate Filament Networks When Expressed in Cultured Cells Thaddeus S. Stappenbeck and Kathleen J. Green Department of Pathology and the Cancer Center, Northwestern University Medical School, Chicago, Illinois 60611 Abstract. Specific interactions between desmoplakins tides including the 90-kD carboxy-terminal globular I and 11 (DP I and II) and other desmosomal or cyto- domain of DP I specifically colocalized with and ulti- skeletal molecules have been difficult to determine in mately resulted in the complete disruption of IF in part because of the complexity and insolubility of the both cell lines. This effect was specific for IF as micro- desmosome and its constituents . We have used a mo- tubule and microfilament networks were unaltered . lecular genetic approach to investigate the role that This effect was also specific for the carboxyl terminus DP I and 11 may play in the association of the desmo- of DP, as the expression of the 95-kD rod domain of somal plaque with cytoplasmic intermediate filaments DP I did not visibly alter IF networks. Immunogold (IF) . A series of mammalian expression vectors en- localization of COS-7 cells transfected with constructs coding specific predicted domains of DP I were tran- including the carboxyl terminus of DP demonstrated siently expressed in cultured cells that form (COS-7) an accumulation of mutant protein in perinuclear aggre- and do not form (NIH-3T3) desmosomes. Sequence gates within which IF subunits were sequestered. -
Bacterial Cell Membrane
BACTERIAL CELL MEMBRANE Dr. Rakesh Sharda Department of Veterinary Microbiology NDVSU College of Veterinary Sc. & A.H., MHOW CYTOPLASMIC MEMBRANE ➢The cytoplasmic membrane, also called a cell membrane or plasma membrane, is about 7 nanometers (nm; 1/1,000,000,000 m) thick. ➢It lies internal to the cell wall and encloses the cytoplasm of the bacterium. ➢It is the most dynamic structure of a prokaryotic cell. Structure of cell membrane ➢The structure of bacterial plasma membrane is that of unit membrane, i.e., a fluid phospholipid bilayer, composed of phospholipids (40%) and peripheral and integral proteins (60%) molecules. ➢The phospholipids of bacterial cell membranes do not contain sterols as in eukaryotes, but instead consist of saturated or monounsaturated fatty acids (rarely, polyunsaturated fatty acids). ➢Many bacteria contain sterol-like molecules called hopanoids. ➢The hopanoids most likely stabilize the bacterial cytoplasmic membrane. ➢The phospholipids are amphoteric molecules with a polar hydrophilic glycerol "head" attached via an ester bond to two non-polar hydrophobic fatty acid tails. ➢The phospholipid bilayer is arranged such that the polar ends of the molecules form the outermost and innermost surface of the membrane while the non-polar ends form the center of the membrane Fluid mosaic model ➢The plasma membrane contains proteins, sugars, and other lipids in addition to the phospholipids. ➢The model that describes the arrangement of these substances in lipid bilayer is called the fluid mosaic model ➢Dispersed within the bilayer are various structural and enzymatic proteins, which carry out most membrane functions. ➢Some membrane proteins are located and function on one side or another of the membrane (peripheral proteins). -
The Endomembrane System and Proteins
Chapter 4 | Cell Structure 121 Endosymbiosis We have mentioned that both mitochondria and chloroplasts contain DNA and ribosomes. Have you wondered why? Strong evidence points to endosymbiosis as the explanation. Symbiosis is a relationship in which organisms from two separate species depend on each other for their survival. Endosymbiosis (endo- = “within”) is a mutually beneficial relationship in which one organism lives inside the other. Endosymbiotic relationships abound in nature. We have already mentioned that microbes that produce vitamin K live inside the human gut. This relationship is beneficial for us because we are unable to synthesize vitamin K. It is also beneficial for the microbes because they are protected from other organisms and from drying out, and they receive abundant food from the environment of the large intestine. Scientists have long noticed that bacteria, mitochondria, and chloroplasts are similar in size. We also know that bacteria have DNA and ribosomes, just like mitochondria and chloroplasts. Scientists believe that host cells and bacteria formed an endosymbiotic relationship when the host cells ingested both aerobic and autotrophic bacteria (cyanobacteria) but did not destroy them. Through many millions of years of evolution, these ingested bacteria became more specialized in their functions, with the aerobic bacteria becoming mitochondria and the autotrophic bacteria becoming chloroplasts. The Central Vacuole Previously, we mentioned vacuoles as essential components of plant cells. If you look at Figure 4.8b, you will see that plant cells each have a large central vacuole that occupies most of the cell's area. The central vacuole plays a key role in regulating the cell’s concentration of water in changing environmental conditions. -
Plakoglobin Is Required for Effective Intermediate Filament Anchorage to Desmosomes Devrim Acehan1, Christopher Petzold1, Iwona Gumper2, David D
ORIGINAL ARTICLE Plakoglobin Is Required for Effective Intermediate Filament Anchorage to Desmosomes Devrim Acehan1, Christopher Petzold1, Iwona Gumper2, David D. Sabatini2, Eliane J. Mu¨ller3, Pamela Cowin2,4 and David L. Stokes1,2,5 Desmosomes are adhesive junctions that provide mechanical coupling between cells. Plakoglobin (PG) is a major component of the intracellular plaque that serves to connect transmembrane elements to the cytoskeleton. We have used electron tomography and immunolabeling to investigate the consequences of PG knockout on the molecular architecture of the intracellular plaque in cultured keratinocytes. Although knockout keratinocytes form substantial numbers of desmosome-like junctions and have a relatively normal intercellular distribution of desmosomal cadherins, their cytoplasmic plaques are sparse and anchoring of intermediate filaments is defective. In the knockout, b-catenin appears to substitute for PG in the clustering of cadherins, but is unable to recruit normal levels of plakophilin-1 and desmoplakin to the plaque. By comparing tomograms of wild type and knockout desmosomes, we have assigned particular densities to desmoplakin and described their interaction with intermediate filaments. Desmoplakin molecules are more extended in wild type than knockout desmosomes, as if intermediate filament connections produced tension within the plaque. On the basis of our observations, we propose a particular assembly sequence, beginning with cadherin clustering within the plasma membrane, followed by recruitment of plakophilin and desmoplakin to the plaque, and ending with anchoring of intermediate filaments, which represents the key to adhesive strength. Journal of Investigative Dermatology (2008) 128, 2665–2675; doi:10.1038/jid.2008.141; published online 22 May 2008 INTRODUCTION dense plaque that is further from the membrane and that Desmosomes are large macromolecular complexes that mediates the binding of intermediate filaments. -
Transiently Structured Head Domains Control Intermediate Filament Assembly
Transiently structured head domains control intermediate filament assembly Xiaoming Zhoua, Yi Lina,1, Masato Katoa,b,c, Eiichiro Morid, Glen Liszczaka, Lillian Sutherlanda, Vasiliy O. Sysoeva, Dylan T. Murraye, Robert Tyckoc, and Steven L. McKnighta,2 aDepartment of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390; bInstitute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 263-8555 Chiba, Japan; cLaboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520; dDepartment of Future Basic Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, Japan; and eDepartment of Chemistry, University of California, Davis, CA 95616 Contributed by Steven L. McKnight, January 2, 2021 (sent for review October 30, 2020; reviewed by Lynette Cegelski, Tatyana Polenova, and Natasha Snider) Low complexity (LC) head domains 92 and 108 residues in length are, IF head domains might facilitate filament assembly in a manner respectively, required for assembly of neurofilament light (NFL) and analogous to LC domain function by RNA-binding proteins in the desmin intermediate filaments (IFs). As studied in isolation, these IF assembly of RNA granules. head domains interconvert between states of conformational disor- IFs are defined by centrally located α-helical segments 300 to der and labile, β-strand–enriched polymers. Solid-state NMR (ss-NMR) 350 residues in length. These central, α-helical segments are spectroscopic studies of NFL and desmin head domain polymers re- flanked on either end by head and tail domains thought to be veal spectral patterns consistent with structural order. -
Cell Wall Ribosomes Nucleus Chloroplast Cytoplasm
Cell Wall Ribosomes Nucleus Nickname: Protector Nickname: Protein Maker Nickname: Brain The cell wall is the outer covering of a Plant cell. It is Ribosomes read the recipe from the The nucleus is the largest organelle in a cell. The a strong and stiff and made of DNA and use this recipe to make nucleus directs all activity in the cell. It also controls cellulose. It supports and protects the plant cell by proteins. The nucleus tells the the growth and reproduction of the cell. holding it upright. It ribosomes which proteins to make. In humans, the nucleus contains 46 chromosomes allows water, oxygen and carbon dioxide to pass in out They are found in both plant and which are the instructions for all the activities in your of plant cell. animal cells. In a cell they can be found cell and body. floating around in the cytoplasm or attached to the endoplasmic reticulum. Chloroplast Cytoplasm Endoplasmic Reticulum Nickname: Oven Nickname: Gel Nickname: Highway Chloroplasts are oval structures that that contain a green Cytoplasm is the gel like fluid inside a The endoplasmic reticulum (ER) is the transportation pigment called chlorophyll. This allows plants to make cell. The organelles are floating around in center for the cell. The ER is like the conveyor belt, you their own food through the process of photosynthesis. this fluid. would see at a supermarket, except instead of moving your groceries it moves proteins from one part of the cell Chloroplasts are necessary for photosynthesis, the food to another. The Endoplasmic Reticulum looks like a making process, to occur. -
Intermediate Filament Accumulation Can Stabilize Microtubules in Caenorhabditis Elegans Motor Neurons
Intermediate filament accumulation can stabilize microtubules in Caenorhabditis elegans motor neurons Naina Kurupa, Yunbo Lia, Alexandr Goncharova, and Yishi Jina,b,1 aNeurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093; and bDepartment of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093 Edited by H. Robert Horvitz, Massachusetts Institute of Technology, Cambridge, MA, and approved February 11, 2018 (received for review December 21, 2017) Neural circuits utilize a coordinated cellular machinery to form and Results eliminate synaptic connections, with the neuronal cytoskeleton Identification of IF Genes That Regulate Synapse Rewiring. At the playing a prominent role. During larval development of Caenorhabditis end of larval stage 1 (L1), the dorsal D (DD)-type motor neurons elegans, synapses of motor neurons are stereotypically rewired rewire their presynaptic connections from the ventral nerve cord through a process facilitated by dynamic microtubules (MTs). Through a (VNC) to the dorsal nerve cord (DNC), concurrent with the genetic suppressor screen on mutant animals that fail to rewire synap- birth of ventral D (VD)-type motor neurons, which then form ses, and in combination with live imaging and ultrastructural studies, synapses along the VNC (19). We visualized DD-neuron pre- we find that intermediate filaments (IFs) stabilize MTs to prevent syn- synaptic terminals using a GFP-tagged synaptobrevin (SNB- apse rewiring. Genetic ablation of IFs or pharmacological disruption of 1::GFP) reporter (juIs137:Pflp-13 SNB-1::GFP). In L1 animals, IF networks restores MT growth and rescues synapse rewiring defects discrete synaptic puncta were present along the ventral neurites in the mutant animals, indicating that IF accumulation directly alters MT (18), but in late larvae and adults, synaptic puncta were only seen stability. -
The Relationship Between Intermediate Filaments and Microfilaments Before and During the Formation of Desmosomes and Adherens-Ty
Published May 1, 1987 The Relationship between Intermediate Filaments and Microfilaments before and during the Formation of Desmosomes and Adherens-type Junctions in Mouse Epidermal Keratinocytes Kathleen J. Green, Benjamin Geiger,* Jonathan C. R. Jones, John C. Talian, and Robert D. Goldman Department of Cell Biology and Anatomy, Northwestern University Medical School, Chicago, Illinois 60611; and * Department of Chemical Immunology, The Weizmann Institute of Science, Rehovot, Israel Abstract. Actin, keratin, vinculin and desmoplakin ermost of the concentric MFB. Individual IF often organization were studied in primary mouse keratino- splay out, becoming interwoven into these MFB in the cytes before and during Ca2+-induced cell contact forma- region of cell-substrate contact. In the first 30 min af- tion. Double-label fluorescence shows that in cells cul- ter the Ca 2+ switch, areas of submembranous dense Downloaded from tured in low Ca 2÷ medium, keratin-containing inter- material (identified as adherens junctions), which are mediate filament bundles (IFB) and desmoplakin- associated with the perpendicular MFB, can be seen at containing spots are both concentrated towards the cell newly formed cell-ceU contact sites. By 1-2 h, IFB- center in a region bounded by a series of concentric desmosomal component complexes are aligned with microfilament bundles (MFB). Within 5-30 min after the perpendicular MFB as the complexes become jcb.rupress.org raising Ca 2+ levels, a discontinuous actin/vinculin-rich, redistributed to cell-cell interfaces. Cytochalasin D submembranous zone of fluorescence appears at cell- treatment causes the redistribution of actin into numer- cell interfaces. This zone is usually associated with ous patches; keratin-containing Lr:B undergo a con- short, perpendicular MFB, which become wider and comitant redistribution, forming foci that coincide with longer with time. -
INTERMEDIATE FILAMENT Dr Krishnendu Das Assistant Professor Department of Zoology City College
INTERMEDIATE FILAMENT Dr Krishnendu Das Assistant Professor Department of Zoology City College Q.What are the intermediate filaments? State their role as cytoskeleton. How its functional significance differs from others? This component of cytoskeleton intermediates between actin filaments (about 7 nm in diameter) and microtubules (about 25 nm in diameter). In contrast to actin filament and microtubule the intermediate filaments are not directly involved in cell movements, instead they appear to play basically a structural role by providing mechanical strength to cells and tissues. (Figure 1: Structure of intermediate filament proteins- intermediate filament proteins contain a central α-helical rod domain of approximately 310 amino acids (350 amino acids in the nuclear lamins). The N-terminal head and C-terminal tail domains vary in size and shape. Q.How intermediate filaments differ from actin filaments and microtubules in respect of their components? Actin filaments and microtubules are polymers of single types of proteins (e.g; actin tubulins), whereas intermediate filaments are composed of a variety of proteins that are expressed in different types of cells (as given in the tabular form) Type Protein Size (kd) Site of expression I Acidic keratin 40-60 Epithelial cells II Neutral or basic keratin 50-70 Do III Vimentin 54 Fibroblasts, WBC and other cell types Desmin 53 Muscle cells Periferin 57 Peripheral neurons IV Neurofilament proteins NF-L 67 Neurons NF-M 150 Neurons NF-H 200 Neurons V Nuclear lamins 60-75 Nuclear lamina of all cell types VI nestin 200 Stem cells, especially of the central nervous system Q.How do intermediate filaments assemble? (Figure 2) The central rod domains of two polypeptides wind around each other in a coiled-coil structure to form dimmers. -
Endomembrane System
Cell Structure & Function Cell Theory Cells are fundamental to biology Cells are the basic living units within organisms (all chemical rxns. of life take place within cells) All organisms are made of cells Single-celled organisms (bacteria/protists) Multicellular organisms (plants/animals/fungi) Cell Structure & Function Basic Aspects of Cell Structure & Function Plasma membrane Lipid bilayer Proteins DNA-containing region Cytoplasm Eukaryotic v. Prokaryotic cells Prokaryotic v. Eukaryotic Cells Two major classes of cells Prokaryotic cells (pro-, “before”) Cell lacks a “true” nucleus DNA is coiled in a nucleoid region Cells lack nuclear membrane Prokaryotic v. Eukaryotic Cells [attachment structure] [DNA location] [organelles that synthesize proteins] [enclosing the cytoplasm] [rigid structure outside the p.m. ] [jelly-like outer coating] [locomotion organelle] Prokaryotic v. Eukaryotic Cells Eukaryotic cells (eu-, “true”) Nucleus contains most of the cells nuclear material, DNA usually the largest organelle Bordered by a membranous envelope Prokaryotic v. Eukaryotic Cells Plant v. Animal Cells Both contain Plasma membrane (functions as a selective barrier) Nucleus (gene-containing organelle) Cytoplasm (region between nucleus and p.m.) Consists of organelles in a fluid (cytosol) Prokaryotic v. Eukaryotic Cells Plant v. Animal Cells Organelles Bordered by internal membranes Compartmentalizes the functions of a cell Maintains organelle’s unique environment Most organelles are found in both plant and animal cells Plant v. Animal Cells -
Cytoskeleton Markers
ptglab.com 1 CYTOSKELETON MARKERS www.ptglab.com Introduction The cytoskeleton is a three-dimensional network supporting and stabilizing the cell. All cells, even bacteria, have a type of cytoskeleton. It is responsible for the shape of the cell and its mechanical properties. Many dynamic cellular processes cooperate with the cytoskeleton, such as cell motion, cell division, intracellular transport, and cell signaling. Therefore, the cytoskeleton interacts with several cytoplasmic proteins or organelles. The cytoskeletal network is composed of three different protein structures named filaments: microtubules, microfilaments (actin), and intermediate filaments. These proteins form their own unique networks within the cell that have different interdependent functions. Main Functions of the Cytoskeleton Structural support Cell trafficking Transducer of mechanical signals Associated with several diseases Cellular signaling Cell Illustrating The Three Different Cytoskeleton Structure Proteins 2 Cytoskeleton Markers Most Popular Antibody Name Catalog Number Type Applications Cytoskeleton Markers ACTA2/alpha 5 23081-1-AP Rabbit Poly ELISA, IHC, IP, WB From Proteintech smooth muscle actin alpha Tubulin 4 11224-1-AP Rabbit Poly ELISA, FC, IF, IHC, IP, WB beta Actin 423 20536-1-AP Rabbit Poly ELISA, IF, IHC, WB beta Actin 399 60008-1-IG Mouse Mono ELISA, FC, IF, IHC, WB beta Tubulin 11 10068-1-AP Rabbit Poly ELISA, IF, IHC, IP, WB Cofilin 5 10960-1-AP Rabbit Poly ELISA, IF, IHC, WB Cytokeratin 17 specific 17516-1-AP Rabbit Poly ELISA, FC, IF, IHC, IP, WB Desmin 2 60226-1-IG Mouse Mono ELISA, IHC, WB GFAP 5 60190-1-IG Mouse Mono ELISA, IF, IHC, IP, WB Palladin 5 10853-1-AP Rabbit Poly ELISA, FC, IF, IHC, IP, WB Vimentin 54 10366-1-AP Rabbit Poly ELISA, FC, IF, IHC, WB 00 This number shows the amount of times our antibody has been cited in a publication. -
Tau Inhibits Vesicle and Organelle Transport
Journal of Cell Science 112, 2355-2367 (1999) 2355 Printed in Great Britain © The Company of Biologists Limited 1999 JCS9926 Tau regulates the attachment/detachment but not the speed of motors in microtubule-dependent transport of single vesicles and organelles B. Trinczek*, A. Ebneth‡, E.-M. Mandelkow and E. Mandelkow* Max-Planck Unit for Structural Molecular Biology, Notkestrasse 85, D-22607 Hamburg, Germany *Authors for correspondence (e-mail: [email protected]; [email protected]) ‡Present address: GENION Forschungsgesellschaft mbH, Abteistrasse 57, 20149 Hamburg, Germany Accepted 30 April; published on WWW 24 June 1999 SUMMARY We have performed a real time analysis of fluorescence- even with that of vimentin intermediate filaments. The net tagged vesicle and mitochondria movement in living CHO effect is a directional bias in the minus-end direction of cells transfected with microtubule-associated protein tau or microtubules which leads to the retraction of mitochondria its microtubule-binding domain. Tau does not alter the or vimentin IFs towards the cell center. The data suggest speed of moving vesicles, but it affects the frequencies of that tau can control intracellular trafficking by affecting attachment and detachment to the microtubule tracks. the attachment and detachment cycle of the motors, in Thus, tau decreases the run lengths both for plus-end and particular by reducing the attachment of kinesin to minus-end directed motion to an equal extent. Reversals microtubules, whereas the movement itself is unaffected. from minus-end to plus-end directed movement of single vesicles are strongly reduced by tau, but reversals in the opposite direction (plus to minus) are not.