Lecture 2 Flashcards
Basal Lamina
Created by Epithelium
Includes: Laminin, Type IV Collagen, Proteoglycans, & Entactin
Binding Site for: Integrins, Type IV Collage, Proteoglycans, & Entactin
Components of the Basement Membrane
Basal Lamina
Reticular Lamina
Reticular Lamina
Created by connective tissue
Non-fibrous
Fibronectin
2 forms: Cellular & Plasma
Binding sites for: Heparin (Proteoglycan), Integrins, Collagen, & Fibrin
Cellular Fibronectin
Produced by fibroblasts, part of extracellular matrix
Plasma Fibronectin
Secreted into bloodstream by hepatocytes
CAM’s
Cell Adhesion Molecules
2 types: Ca++ dependent & Ca++ independent
Ca++ Dependent CAM’s
Cadherins & Selectins
Ca++ Independent CAM’s
Integrins & Immunoglobulin Superfamily
Cadherins
Classical & Non-classical
Classical Cadherins
Form Cis- & Trans- homophilic dimers
Cis: within the same cell
Trans: cell-cell
Include E, N, & P Cadherins: Epithelial, Nerve, Placenta
Nonclassical Cadherins
Found in Desmosomes
Include Desmocollins & Desmogleins
E-Cadherins
Trans-membrane molecules
Form dimers using HVA binding sites
HVA binding sites
Facilitate formation of trans-homophilic dimers with cadherins of neighboring cell
Catenins
Small proteins that link cytoplasmic end of cadherin with cytoplasmic actin
Selectins
Contain Carbohydrate Recognition Domain (CRD) at extracellular end that bind to carbohydrates
Ca++ binding sites also near CRD, Ca++ required for binding to occur
Involved in moving leukocytes out of blood stream (extravasation)
Types of Selectins
P-platelet selectins
E-endothelial selectins
L-leukocytes
Integrins
Glycoproteins involved in cell-extracellular matrix interactions
Bind to extracellular matrix and cytoskeleton
Bind to Fibronectin and Laminin in extracellular matrix
Where are Laminin and Fibronectin located and what do they interact with…
Located in basement membrane
Interact with Collagen, Heparan Sulfate Proteoglycans, & Entactin
Hemidesmosomes/Desmosomes
Hemidesmosomes- only at basal domain, attach via extracellular matrix and tonofilaments (keratin) in intracellular matrix
Desmosomes- bind one cell to a neighboring cell
Immunoglobulin Superfamily
Posses an extracellular segment with one or more folded domains
Members of the Ig-Superfamily
N-CAMs: neural adhesion molecules that aid in homo- and hetero- philic interactions
I-CAM-1 & I-CAM-2: facilitate transendothelial transport of leukocytes
Adherens
Molelcular complexes that anchor cells together and reinforce physical integrity of tissues
Found on basolateral surface of epithelial cells
Occludens
Molecular complexes that establish an impermeable membrane b/w cells that prohibits paracellular transport
Gap Junctions
Pores in cells that allow for quick exchange of small molecules/ions
Can be added or taken out of cell when necessary
Composed of Connexons which consist of 6 Connexins in hexagonal structure
Close when [Ca++] is high
Zonula Adheren
Type of junctional complex
aka Belt-like complexes
Travel full circumference of cell attaching all neighboring cells to a central cell
Associated with actin microfilaments
Macula Adheren
Type of junctional complex
“Spot” adherens referred to as Desmosomes (lateral sides)/Hemidesmosomes (basal side) of epithelial cells
Associated with tonofilaments
Zonula Occluden
Belt-like, tight junctions that provide of barrier against the paracellular transport pathway
JAM’s
Junctional Adhesion Molecules
Part of immunogloblulin superfamily
Form cis- homodimers that facilitate adhesion
Nectin
Part of immunoglobulin superfamily
Form cis- homodimers to facilitate adhesion
Focal Adhesions
Spots that anchor the cell to the extracellular matrix via integrins
Bind to actin intracellularly, unlike desmosomes which bind to tonofilaments
