Lecture 3-Cell Junctions/Surface Specializations Flashcards
2 classes of cell adhesion molecoules
Calcium dependent=cadherins, selectins
Calcium independent=integrins, immunoglobulin
Cadherins require calcium and maintain _____. They are are stabilized by an ____ cytoskeleton.
cell-cell contacts
actin
Binding of actin to cadherins is via ___
catenins
Loss of E-caderhin is associated with
tumor metastisis
Selectins require calcium and bind to ___ at ____ recognition domains
carbohydrates, carbohydrate
Selectins are found on ___ and blood cells, and are important for controlling movement of leukocytes from blood into tissues
endothelia
If you add a ____ agent to Calcium dependent adhesion molecoules, Ca will bind the agent and cells will ____
celating
come apart
Integrins are not calcium dependent. The binding site of integrin is on its _____ subunit (alpha or beta).
beta
The intracellular part of integrin binds to cytoskeletal ____ via binding proteins, while the extracellular portion binds to other ligands (ie laminin, fibronectin, tenascin, vitronectin.)
actin
bound via talin, viniculin, alpha actin
Immunoglobulins consist of a _____ on the extracellular portion of the cell.
Cell adhesion molecoule
____ and ____ molecoules play an important role in T cell interactions and binding of leukocytes to activated endothelial cells. (part of IgG super family)
ICAM and VCAM
_____ junctions determine epithelia polarity and prevent free passage across an epithelial layer by ions/proteins
Occluding (tight)
They separate the apical domain from the baolateral domain)
Occluding junctions interact with these 2 transmembrane proteins
Occludin and claudin
Nectins and Junctional Adhesion Molecoules (JAMS are present in ____ junctions.
Tight
Interaction between occludin and claudin regulates the _____ pathway
paracellular
A gene mutation in Claudin 16 causes
renal magnesium wasting syndrome
Tight Junctions are important parts of the blood brain barrier and can prevent ____
delivery of drugs
_____ are located below occulding juctions
Zonula Adherens
Zonula Adherens consist primarily of interactions between ____ and ____. They form a belt-like distribution around the cell
cadherins and catenins
Zonula adherens form a strong association due to interaction with ____ filaments in the cytoskeleton
Actin
Desmosomes are spot like junctions and are stabilized by _____
intermediate filaments-including keratin and vimentin
Pemphigus foliaceus is an autoantibody-mediated blistering disease in which antibodies against _____ cause a loss of adhesion of keratinocytes in the superficial layers of the epidermis
desmoglein 1
______ anchor the basal portion of a cell to the basal lamina
hemidesmosomes
Hemidesmosomes are the only ____ junction
assymetrical
Hemidesmosomes consist of intermediate filaments bound to a protein complex containing ____. The comple is linked by integrins to the basal lamina by ____
plectin, laminin
_____ junctions are communicating junctions between cells
Gap
In gap junctions, 6 integral proteins called ___ associate to form ____
connexins, connexon
Gap junctions link cells both chemically and _____ and are found in _____ muscle cells
electrically, cardiac
A mutation in connexin 26 causes ____. A mutation in connexin 32 causes ______ _____ degeneration. Connexin 50 mutations can cause _____
deafness
peripheral nerve (aka Charcot-Marie-Tooth neuropothies)
cataracts and blindness
_____ increase surface area for absorption and contain an actin filament core that links into the _____ web.
Microvilli
Terminal
Microvilli are often found in the ____
small intestine
Cillia and flagella both have a ____ array of highly stable MTs
9 + 2
Cilia consists of hairlike appendages that move fluid and develop from ____ bodies
basal
2 functions of cilia: 1 in lung, 1 dealing with reproduction
sweep mucus and particulates away in lung
move egg to oviduct
Flagella act as propellor for _____ motility. ____ provides force for movement
sperm, dyneins
Loss of dynein in cilia leads to _____ syndrome, which causes poor respiratory clearance
kartagener’s
Stereocilia have similar structure to microvilli but differ in that they are _____ and _____
longer and branch
Stereocilia are typical of the ____ epithelium and cause an increase in ______
epididymal
surface area
Leucocyte adhesion deficiency type 1 is characterized by recurren infections and is caused by mutations of _____
integrin
Autosomal recessive glanzmann thrombasthenia is due to point mutations in _____
integrin
Congenitial Muscular Dystrophy results in muscle weakness and is due to defects in the cytoskeletal linker protein ____
dystrophin
it is a major laminin binding integrin species
Removal of calcium stops adhesion and makes ______ vulnerable to proteases
cadherins
______ are important for controlling movement of leukocytes from blood into tissues
selectins
_____ junctions are at the most apical portion of epithelium and define cell polarity.
Occluding
_____ adherens is associated with actin and has a while beltlike distribution.
Zonula
_____ adherens is associated with Intermediate filaments and has a spotlike distribution
Macula
basal bodies of cilia are derived from _____
centrioles
Autosomal recessive Glanzmann thrombaasthenia is due to integrin dysfunction and results in _____ dysfunction as well as prolonged bleeding time
platelet
______ bullosa causes disruption of the mechanical link between the basement membrane and the basal keratinocyte layer
Epidermolysis
