Cell Junctions - Tight Junctions and Adherens Junctions
There are a number of specialized junctional complexes in epithelial cells, formed by molecules that are different from CAMs and SAMs. These comprise of tight junctions, gap junctions, adherens junctions, and desmosomes; gap junctions can in addition form stuck between cell aggregates in condensing mesenchyme. All of these are well-formed and sometimes elaborate supramolecular structures carrying out various functions, ranging from electrical and chemical cell-cell message (gap junctions) to sealing apical surfaces of epithelia (tight junctions) or linking defined regions of cell-cell contact with cytoskeletal elements (adherens junctions, desmosomes). We will regard these structures in order, paying nearly all attention to their possible functions in embryogenesis and morphogenesis.
These are comprised from oligomeric membrane protein subunits that unite in defined structures (connexons). Connexons interrelate throughout the space stuck between apposed cells and allow straight pathways (channels) for communication from cell...
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