How is stress transmitted in epithelial tissue vs connective tissue?
4 Types of cell junctions in animal cells?
– Include cell-cell and cell-matrix interactions
– Transmit external stress from across the plasma membrane to the underlying cytoskeleton
– Form a permeability barrier between cells in an epithelia sheet
Channel forming Junctions
– Create cytoplasmic continuity between adjacent cells for the passage of small molecules
Signal Relay Junctions
– Allows extracellular signals to be passed from one cell to another
– Some anchoring junctions and channel forming junctions also conduct signaling
adherens junctions and desmosomes are ___
cell-cell anchoring junctions
actin-linked cell matrix junctions and hemidesmosomes are____
cell-matrix anchoring junctions
tight junctions are ___
Gap junctions are ___
channel forming junctions
seals gap between epithelial cells
connects actin filament bundle in one cell with that in the next cell
connects intermediate filaments in one cell to those in the next cell
allows the passage of small water-soluble molecules from cell to cell
actin-linked cell-matrix junction
anchors actin filaments in cell to extracellular matrix
anchors intermediate filaments in a cell to extracellular matrix
_____ link the cytoskeleton to extracellular structures
Cell-cell interactions are mediated by the ____ family of transmembrane anchors
Cell-Matrix interactions are mediated by the ____ family of transmembrane anchors
Anchoring Junctions function
• Provide mechanical strength
– Especially important to tissues encountering severe mechanical stress like heart, muscle, and skin
• Connect the cytoskeleton to neighboring cells or the extracellular matrix
Anchoring Junctions are composed of what two main classes of proteins?
– Intercellular anchor proteins
– Transmembrane adhesion proteins
Types of Anchor Junctions
– Adherens junctions
– Focal Adhesions
• Ca2+-dependent cell-cell adhesion
• Present in adherens junctions and desmosomes
• Found in virtually all cells and tissues
Cadherins mediate ____ adhesion
Cadherin structure and function
How do cadherins play a role in development?
Cell with similiar subclasses of cadherins expressed on their surface stick together because of homophilic binding
Cadherins mediate cell-cell adhesion by a homophilic mechanism
• Tissue culture cells (that normally do not express N or E-cadherins) can be made to express either N- or Ecadherin.
• The resulting population self selects based on homophilic interaction of the individual cadherins
Which proteins link cadherins to actin filaments?