What provides a means for anchoring cells between adjacent epithelial cells and the basal laminae?
Adhesions and junctions
What are the 4 types of Intercellular adhesions and other junctions?
Tight junctions, Adherins, Gap junctions, hemidesmosomes
Tight junction is also known as what?
Occluding junctions
Adherens is also known as what?
Anchoring junctions
Tight or occluding junctions: form a seal between ADJACENT cells
Adherens of anchoring junctions: sites of strong cell adhesion
Gap junctions: channels for communication between adjacent cells
Hemidesmosomes: anchors cells to the basal lamina
Tight junctions are also known as what?
Zonulae occludens
What type of junction are the MOST APICAL?
Tight junctions
In tight junction, the seal between the two cell membranes is due to tight interactions between the transmembrane proteins what?
claudins and occludin
Tight junctions: serve as fences restricting movements of membrane lipids and proteins at the apical cell surface into the lateral and basal surfaces, and vice versa.
Adherens junction is also known as what?
Zonula adherens
What type of junction is immediately below the TIGHT JUNCTION?
Adherens junction
Adherens junctions firmly anchors a cell to its neigbors mediated by what?
Cadherins
At their cytoplasmic ends, cadherins bind to what that link to actin filaments with actin-binding proteins?
Catenins
The actin filaments linked to the adherens junctions form part of the “TERMINAL WEB,” a cytoskeletal feature at the apical pole in many epithelial cells
Desmosomes is also known as what?
Macula adherens
What type of junction resembles a single “spot-weld” and does not form a belt around the cell?
Desmosomes
Desmosomes: disc-shaped structures at the surface of one cell that are matched with identical structures at an adjacent cell surface - provide firm cellular ad
Gap junctions: mediate intercellular communication rather than adhesion or occlusion between cells
What type of junction is functionally important in nearly all mammalian tissues as, it permit intercellular exchange of molecules with small ( <1.5 nm) diameters?
Gap junctions
INTEGRINS of hemidesmosomes bind primarily to LAMININ molecules in the basal lamina
Which among the junction has NO cytoskeletal component?
Gap junction
Gap junctions: allows DIRECT TRANSFER of small molecules and ions from one cell to another.
Desmosome: Autoimmunity against DESMOGLEIN I leads to dyshesive skin disorders characterized by reduced cohesion of epidermal cells
Gap junctions: Mutations in various CONNEXIN genes have been linked to certain types of DEAFNESS and peripheral neuropathy
HEMIDESMOSOME: Mutations in INTEGRIN-B4 gene are linked to some types of EPIDERMOLYSIS BULLOSA, a skin blistering disorder
DESMOSOME: Cadherin family proteins like desmogleins and desmocolin
TIGHT JUNCTION: Seals ADJACENT CELLS to one another, controlling passage of molecules between them, separates apical and basolateral membrane domains
What is the cytoskeletal component of tight junction?
Actin filament
Adherent junction: LOSS of E-cadherin in epithelial cell tumors (carcinomas) promotes tumor invasion and the shift to malignancy
What type of cytoskeletal component do hemidesmosome have?
Intermediate filaments
What type of cytoskeletal component do adherent junction have?
actin filaments
Gap junction: connexin
HEMIDESMOSOME: Integrins
ADHERENT JUNCTION: Provides points linking the cytoskeletons of adjacent cells; strengthens and stabilizes nearby tight junctions
ADHERENT JUNCTION: E-cadherin and catenin complexes
HEMIDESMOSOME: Anchors cytoskeleton to the basal lamina