Cell Conjunctions

Factors binding epithelial cells together

• Adhesion proteins link plasma membranes of

adjacent cells

• Contours of adjacent cell membranes

• Special cell junctions

Tight junctions (seal) (zona occludens)—close off

intercellular space

Found at apical region of most epithelial tissues

types

• Some proteins in plasma membrane of adjacent

cells are fused

• Prevent certain molecules from passing between

cells of epithelial tissue

Adhesive belt junctions

Transmembrane linker proteins attach to actin

microfilaments of the cytoskeleton and bind

adjacent cells

• With tight junctions, these linker proteins form the

tight junctional complex around apical lateral

borders of epithelial tissue

Desmosomes junction (main junctions for binding cells

together)

Scattered along abutting sides of adjacent cells

• Cytoplasmic side of each plasma membrane has

a plaque

• Plaques are joined by linker proteins

intermediate filaments extend across the

cytoplasm and anchor at desmosomes on

opposite side of the cell

• Are common in cardiac muscle and epithelial

tissue

Gap junctions—passageway between two

adjacent cells

• These let small molecules move directly

between neighboring cells

• Cells are connected by hollow cylinders of

protein

• Function in intercellular communication