Cytoskeleton (W8)

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    Created by
    Megan Lui

    Cards (25)

    • 3 cytoskeleton filaments
      1. Actin filaments / Microfilaments
      2. Microtubules
      3. Intermediate filaments
    • Microfilaments
      Subunit: ATP-Actin
      No. of protofilament: 2
      Polarity: Yes
    • Microfilaments
      Diameter: 8nm
      Organisation: networks or parallel filaments
      Structure: flexible
    • Microfilament
      Function: cell shape, contraction and migration
      Polymerisation dynamic: treadmilling
      Subcellular distribution: cytoplasm, underneath membrane
    • Microtubules
      Subunit: a/B tubulin (dimer)
      No. of protofilaments: 13
      Polarity: Yes
    • Microtubules
      Diameter: 25nm
      Organisation: hollow cylindrical tubes
      Structure: stiff
    • Microtubules
      Functions: intracellular trafficking, organisation and mitotic spindle
      Polymerisation dynamic: dynamic instability
      Subcellular distribution: Cytoplasm (extends from centre of cell)
    • Microfilaments
      Enzymatic activity: Yes, ATPase
      Motor proteins: myosin
    • Microtubules
      Enzymatic activity: Yes, GTPase
      Motor proteins: Kinesin, Dynein
    • Intermediate filaments
      Subunit: multiple types (fibrous)
      No. of protofilaments: 8 tetramers
      Polarity: No
    • Intermediate filaments
      Diameter: 10nm
      Organisation: rope-like staggered tetramers
      Structure: strong, tough, durable
    • Intermediate filaments
      Function: mechanical strength
      Polymerisation dynamic: stable, low turnover
      Subcellular distribution: cytoplasm and nucleus
    • Intermediate filaments
      Enzymatic activity: None
      Motor protein: None
    • Function of anchoring junctions
      Anchor the cytoskeleton between cells or between cells and extracellular matrix (ECM)
    • Function of occluding junctions
      Prevents the passage of ions and small molecules between cells
    • Function of communicating junction
      Direct connections between the cytoplasm of 2 cells
    • Types of anchoring junctions
      • Adherens
      • Desmosomes
      • Focal adhesions
      • Hemidesmosomes
    • Types of occluding junctions
      • Tight
    • Communicating junctions
      • Gap
    • Tight junctions
      Between: 2 cells
      Function: seal gaps between cells, prevent diffusion
      Proteins: claudins and occludins
      Multi pass
    • Adherens junctions
      Between: 2 cells
      Function: cell-cell adhesion, regulation of actin cytoskeleton, signalling
      Proteins: cadherins
      Single pass
      Cytoskeleton: actin filaments
      Adaptor proteins: catenin
    • Gap junction
      Between: 2 cells
      Function: provide channels which connect the cytoplasm of 2 cells
      Proteins: connexins
      Single pass
    • Desmosomes
      Between: 2 cells
      Function: strong adhesion, resistance to mechanical stress, signalling
      Proteins: cadherins
      Single pass
      Cytoskeleton: intermediate filaments
      Adaptor protein: plaque
    • Hemidesmosomes
      Between: cell and ECM
      Function: stable adhesion of basal epithelial cells to basement membrane
      Proteins: integrins
      Single pass
      Cytoskeleton: intermediate filament
      Adaptor proteins: plaque
    • Focal adhesions
      Between: cell and ECM
      Function: cell-ECM adhesion, signal transduction and cell migration
      Proteins: integrins
      Single pass
      Cytoskeleton: microfilaments
      Adaptor proteins: talin and vinculin
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