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Intermediate Filaments: Cytoplasmic filaments intermediate in diameter (about 10 nanometers) between the microfilaments and the microtubules. They may be composed of any of a number of different proteins and form a ring around the cell nucleus.

Cytoplasm

JoVE 10967

The cytoplasm consists of organelles, an aqueous solution called the cytosol, and a framework of protein scaffolds called the cytoskeleton. The cytosol is a rich broth of ions, small organic molecules such as glucose, and macromolecules such as proteins. Several cellular processes including protein synthesis occur in the cytoplasm.

The composition of the cytosol promotes protein folding such that hydrophobic amino acid side chains are oriented away from the aqueous solution and towards the protein core. However, cellular stressors such as aging and changes in pH, temperature, or osmolarity cause protein misfolding. Misfolded proteins may aggregate to form insoluble deposits in the cytoplasm. Insoluble protein aggregates are implicated in neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. The eukaryotic cytoskeleton consists of three types of filamentous proteins: microtubules, microfilaments, and intermediate filaments. Microtubules–the largest type of filament–are made up of the protein tubulin. Microtubules are dynamic structures that can grow or shrink by adding or removing tubulin molecules from the ends of their strands. They provide structural stability and provide tracks for the transport of proteins and vesicles within the cell. In addition, microtubules play a

 Core: Cell Structure and Function

Microtubules

JoVE 10693

There are three types of cytoskeletal structures in eukaryotic cells—microfilaments, intermediate filaments, and microtubules. With a diameter of about 25 nm, microtubules are the thickest of these fibers. Microtubules carry out a variety of functions that include cell structure and support, transport of organelles, cell motility (movement), and the separation of chromosomes during cell division. Microtubules are hollow tubes whose walls are made up of globular tubulin proteins. Each tubulin molecule is a heterodimer, consisting of a subunit of α-tubulin and a subunit of β-tubulin. The dimers are arranged in linear rows called protofilaments. A microtubule usually consists of 13 protofilaments, arranged side by side, wrapped around the hollow core. Because of this arrangement, microtubules are polar, meaning that they have different ends. The plus end has β-tubulin exposed, and the minus end has α-tubulin exposed. Microtubules can rapidly assemble—grow in length through polymerization of tubulin molecules—and disassemble. The two ends behave differently in this regard. The plus end is typically the fast-growing end or the end where tubulin is added, and the minus end is the slow-growing end or the end where tubulin dissociates—depending on the situation. This process of dynamic instability, where microtu

 Core: Cell Structure and Function

The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging

1Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital, Harvard Medical School, 2College of Life Sciences, Jilin University, 3Faculty of Health Sciences, University of Macau

JoVE 56100

 Developmental Biology

3-D Cell Culture System for Studying Invasion and Evaluating Therapeutics in Bladder Cancer

1Departments of Internal Medicine, Hematology/Oncology Division, Rogel Cancer Center, University of Michigan Medical Center, 2Department of Urology, Division of GU Oncology, Rogel Cancer Center, University of Michigan Medical Center, 3Departments of Surgery and Pathology, Perlmutter Cancer Center, NYU Langone Health

JoVE 58345

 Cancer Research

Analysis of Retinoic Acid-induced Neural Differentiation of Mouse Embryonic Stem Cells in Two and Three-dimensional Embryoid Bodies

1Department of Medicine, Cardeza Vascular Research Center, Sidney Kimmel Medical College, Thomas Jefferson University, 2Department of Molecular Cardiology, Cleveland Clinic Foundation, 3Department of Cancer Biology, Cardeza Vascular Research Center, Sidney Kimmel Medical College, Thomas Jefferson University

JoVE 55621

 Developmental Biology

Purification of Mouse Brain Vessels

1Collège de France, Center for Interdisciplinary Research in Biology (CIRB), Centre National de la Recherche Scientifique CNRS, Unité Mixte de Recherche 7241, Institut National de la Santé et de la Recherche Médicale, 2Centre Interdisciplinaire de Recherche en Biologie, 3MEMOLIFE Laboratory of Excellence and Paris Science, Lettre Research University, 4Université Paris Descartes, Faculté de Pharmacie, Université Paris Diderot

JoVE 53208

 Neuroscience
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