Lecture 5 - Epithelial Tissues: Cell adhesion molecules (CAMS) Flashcards
What are Gap junctions?
These are composed of molecular pores that enable cells to rapid exchange of ions and small molecules that help coordinate activities among the cells that make up the tissue
What does fibronectin binds too?
Heparin (proteoglycan)
Integrins
Collagens
Fibrin
What are occludens?
The molecular complex that establish the impermeable barrier b/w adjacent cells , especially epithelial cells, that prevents para-celluar transport and maintains concentration differences b/w the environment on either side the epithelial sheets
What are names of basement membrane componets and their respective origins?
- Basal Lamina which is derivived from the EPithelial Layer
- Rectuclar Lamina which comes from Connective TIssue
THey both contain glycoproteins and are pas +
Why are selectins classified as lectins and what is their functon?
- Because they have CRB (carbohydrate recongition Domain) region which causes it to bind to carbohydrates.
- involved in the mvement of leukocytes from blood to tissues
- called extravasation
What is the most common type of cadherin (the one that assists in invasive behavior of tumer cells ?
E cadherin
Forms H-V-A binding face
Cis homophillic dimer
loss of e-cadherins asocated w. this behavior
What is the major componet of the basal lamina and what is its characteristics ?
- Consists of α, β, γ chains
- its binding sites are
- Integrins,
- type IV collagen
- Enactin
- Proteoglyicans (heparan sulfate)
What are the characteristics of fibronectin?
- Mad up of two peptide chains
- linked by disulfide bonds
- existis in two forms
- Ceullular -> produce by fibroblasts and part of ECM
- Plasma - > Secreted into blood stream by heaptocytes
What is the structure of of the hemidesmosome?
- Anchors junctions that anchor the basa domain of epitheial cell to basal lamina
- srtucture
- cytoplasmc plate assocaiated w/ intermediate filaments such as keratin
- membrane plaque linking hemidesmosome to basal lamina via anchoring filaments (laminin 5) and Integrins (integrin alpha 6 beta 4)
KNOW THIS
What is the molecular structure of Zonula Adherens
- The cadherin proteins are anchored to cytoplasmic plaques containing:
- Desmoplakin
- Plakoglobin
- actin filaments
- afladin linked via afladin and nectin complex
- catinen linked cadherins (desmocollin and desmoglein)
What are the 3 classes of cadherins and indicate where they are located?
E cadherin -> epithelial Tissues
N cadherin -> Nerve Cells
P cadherin -> placenta
(there are nonclassical ones two)
Democollin and desmoglein in desmosomes (macula adherin)
hat are the components of Basal Lamina and the type of collagen assocated with it?
laminin
Fibonectin
Collagin IV (does not form fibers and is secreted from epitherlial T)
Enactin (nidogen)
Proteoglycans
What is the major function of integrins?
- glycoproteins that are involved with cell to extracelluar interactions
- bind to both ECM and Cytoskeleten
- Two subunits alpha and beta
- ECM binds domain of integrin binds to lamin and fibronectin
- the RGD (Arg-Gly-Asp) region
KNOW THIS
What is the molecular structure of macula adherens?
Macula adherens associated with keratin intermediate fialmetns (tonofilaments)
cyopplasmic palques linked by cadherins (desmocollins and desmogleins)
What is the structure of zonula occuldins?
- Claudins and Occludins transmembranal proteins that are assocated with the junctional complex
- Attach intracellulary to zonula occludens proteins ZO-2 and zo-3
- Includes junctional adhesion molecules (JAMS) bind to both afadin and zo1
- nectin vinds to intracellular molecule molecule alfadin
- zonula occludens proteins and afadin faciliate interactions w. intracellular actin filaments
