CAMs & Junctional Complexes Flashcards
(46 cards)
what are characteristics of the basement membrane
separates an epithelial layer from its connective tissue support
is approximately 50-88nm thick
2 components: basal lamina and reticular lamina
What are the 2 components of the basement membrane and what are they produced from
Basal lamina: produced by the epithelium
Reticular lamina: produced by the connective tissue
define the basement membrane
extracellular component in direct contact with the basal domain of epithelial cells
what are characteristics of laminin
major component of basal lamina: consists of 3 chains (alpha, beta, gamma)
has binding sites for integrins, type IV collagen, entactin & proteoglycans
what are the characteristics of fibronectin
protein made up of 2 polypeptide chains cross-linked by disulfide bonds
forms: cellular and plasma
has binding sites for: Heparin, Integrins, Collagen, Fibrin
decipher between plasma fibronectin and cellular fibronectin
plasma is produced by hepatocytes and secreted into the bloodstream; cellular is produced by fibroblasts and forms part of the extracellular matrix
what are the 2 calcium dependent CAMs
cadherins
selectins
what are the calcium independent CAMs
integrins
immunoglobulin superfamily molecules
what ligands do cadherins recognize and what are the stable types of junctions
ligands: other cadherins
junctions: occludes and desmosomes
what ligands do selections recognize and what are the stable types of junctions
ligands: carbohydrates
junctions: none
what ligands do integrins recognize and what are the stable types of junctions
ligands: extracellular matrix molecules
junctions: hemidesmosomes
what ligands do Ig Superfamily recognize and what are the stable types of junctions
ligands: integrins
junctions: none
what are the 3 types of classical cadherins and where are they found
E: found in epithelial tissues
N: found in nerve cells
P: found in placenta
what are the types of non-classical cadherins and where are they found
desmocollins and desmogleins
found in desmosomes
what is the most common type of cadherin?
E-cadherin
what is the loss of e-cadherin associated with
invasive behavior of tumor cells
how do E-cadherins form dimers
via a HVA binding face (Histidine-Valine-Alanine sequence)
what are catenins?
small proteins that link the cytoplasmic end of cadherin with cytoplasmic actin
what are the 3 forms of catenins & what do they do
B and gamma plakoglobin catenins: attach to cytoplasmic end of cadherin, Beta may also serve as a transcription cofactor, Beta is also attached to alpha catenin
Alpha: Binds directly to cytoplasmic actin (interface between cadherin and actin cytoskeleton)
What serves as a major interface between the cadherins that hold adjacent cells together and the actin cytoskeletons of those cells
Catenins
what are characteristics of selectins
bind to carbohydrates (belong to lectin group)
involved in the movement of leukocytes from blood to tissues
what are the 3 main classes of selections and what are they associated with
P: associated with platelets
E: associated with activated endothelial cells
L: associated with leukocytes
what are characteristics of integrins
- they are glycoproteins that are mainly involved in cell-extracelllular matrix interactions
- bind to both extracellular matrix and cytoskeleton
- 2 subunits: one alpha (17 kinds) and one beta (8 kinds)
- Extracellular domains of integrins bind to molecules in the extracellular matrix such as fibronectin and laminin
- interact with the RGD (Arg-Gly-Asp) sequence in fibronectin and laminin
what do the laminin and fibronectin in the basement membrane interact with
collagen
heparan sulfate proteoglycans
entactin