Lecture 5: CAMs Flashcards
Calcium independent CAMs
Integrins
Immunoglobulin superfamily molecules
What is fibronectin
Protein made up of two polypeptide chains cross-linked by disulfide bonds
Gap junction function
Composed of molecular pores that allow cells to rapidly exchange ions and small molecules
Classes of cadherins and their locations
E-Cadherins–Epithelial tissues
N-Cadherins–Nerve cells
P-Cadherins–Pacenta
Laminin has binding sites for
Integrins
Type IV collagen
Entactin
Proteoglycans
Classes of Selectins and their functions
P-Selectins–Associated with platelets
E-Selectins–Associated with activated endothelial cells
L-Selectins–Associated with leukocytes
Function of integrins in hemidesmosomes
Link the basil domain of the cell to the extracellular matrix via the intercellular tonofilamints (intermediate filaments such as keratin)
Components of basil lamina
Laminin Fibronectin Type IV collagen Entactin Proteoglycans
Selectin function
Selectins are involved in the movement of leukocytes from blood to tissues (extravasation)
Members of immunoglobulin superfamily and function
N-CAM- Neural adhesion molecues
I-CAM1- Facilitates transendothelial migration of leukocytes
I-CAM2
Nonclassical cadherins
Include desmocollins and desmogleins
Found in desmosomes (macula adherens)
E-Cadherins
Most common type
Loss of E-Cadherin is associated with invasive behavior of tumor cells
Basement membrane components
Basil lamina
Reticular lamina
Hemidesmosomes structure/function
Link basal domain to basal lamina via intermediate filaments which associate with intracellular plaques which associate with integrin and anchoring filaments (laminin 5)
What are integrins
Glycoproteins that are mainly involved in cell-extracellular matrix interactions
Gap junctions are composed of ____ , which form what
Connexons, form hydrophillic intercellular channel between adjacent cells
Integrins bind what together
Extracellular matrix molecules and the cytoskeleton
Three chains of laminin
Alpha
Beta
Delta
Zonula-type of junction, function, filament association
Adheren or occluden
Travel all the way around the circumference of the cell and link all neighboring cells to the central cell (belt-like)
Associated with intracellular actin
What are Catenins
Small proteins that link the cytoplasmic end of a cadherin with the cytoplasmic actin
Focal adhesions
Spots that anchor the cell to the extracellular matrix via integrins
What is the CRD
Carbohydrate recognition domain-binding site for carbohydrates on selectins
Calcium is required for binding
Basil lamina produced by
Epithelium
Zonula occluden structure/function
Belt-like structure preventing paracellular transport
Associated transmembrane proteins include occludens and claudins. They attach intracellularly to zonula occluden proteins ZO-2 & ZO-3, which attach to actin
Reticular lamina produced by
Connective tissue
Why are selectins classified as lectins
Because they bind to carbohydrates
Adheren function and location
Anchor cells together and reinforce the physical integrity of tissues and cells that make up tissues
Found on basolateral domain of epithelial cells
Calcium dependent CAMs
Cadherins
Selectins
Connexons are composed of
6 Connexins
Cadherin proteins are anchored by
Intracellular plaques
Adherens characterized by
Intercellular spaces which are filled with cadherin proteins desmogleins and desmocollins
Macula- type of junction, function, filament association
Adheren (often referred to as desmosomes or hemides)
A “spot” or snap-like junction
Associated with intracellular intermediate filaments
(tonofilaments)
Pemphigus foliaceus
Autoantibody-mediated blistering disease in which antibodies against desmoglein-1 cause a loss of adhesion of keratinocytes in the superficial layers of epidermis
Extracellular domain of integrins bind to what
Extracellular matrix molecules such as fibronectin and laminin
Categories of junctional complexes
Adherens
Occludens
Gap junctions
Fibronectin has binding sites for
Integrins
Collagen
Heparin (proteoglycan)
Fibrin
Major component of basil lamina
Laminin
Forms of fibronectin
Cellular (produced by fibroblasts)
Plasma
Occluden function
Establish impermeable barrier between adjacent cells
Maintains concentration differences between
environments on either side of epithelial sheets
