Lecture 5: Cell Adhesion Molecules Flashcards
Name the two components of the Basement Membrane
basal lamina
reticular lamina
what does the basement membrane separate?
an epithelial layer from it’s CT support
what is the average thickness of the basement membrane?
50-80 nm thick
which component of the basement membrane is produced by the epithelium?
basal lamina
which component of the basement membrane is produced by the connective tissue?
reticular lamina
name the five components of the basal lamina
laminin fibronectin type IV collagen entactin proteoglycans
name two ways type IV collagen differs from type I
does not form fibrils
is produced by epithelial cells, type I is produced by fibroblasts
which of the five components of the basal lamina is the major component?
laminin
Laminin consists of how many chains? and what are their names?
3 chains
alpha, beta, gamma
Laminin has binding sites for 4 molecules, name the four molecules that bind….
integrins, type IV collagen, entactin, proteoglycans
a protein made up of two polypeptide chains that are cross-linked by disulfide bonds.….?
Fibronectin
Fibronectin comes in 2 forms, name them
Cellular form and plasma form
The cellular form of _____ protein, is produced by fibroblasts…..
fibronectin
the plasma form of fibronectin is secreted into the bloodstream by what cells?
hepatocytes
Heparin is what type of molecule?
proteoglycan
Fibronectin has binding sites for 4 molecules, name them…..
integrins, collagen, fibrin, proteoglycans(heparin)
True or False: Fibronectin and Laminin both have binding sites for 5 different molecules
False: they both bind 4
What does CAM stand for?
cell adhesion molecules
CAMs are divided into 2 groups, depending upon their need for ______ in their interactions with other molecules.
Calcium ions
Name the 2 groups of CAMs
calcium dependent
calcium independent
Cadherins & Selectins belong to which group of CAMs?
calcium dependent
Integrins & Immunoglobulin superfamily molecules, belong to which groups of CAMs?
calcium independent
Which CAM binds to cadherins?
cadherins
Which CAM binds to carbohydrates?
selectins
This CAM binds to molecules in the extracellular matrix….
Integrins
This CAM binds to Integrins…..
immunoglobulin superfamily molecules
Name the four CAMs we discussed in class
cadherins
selectins
integrins
Ig Superfamily
Which CAMs form stable types of junctions?
Cadherins & Integrins
_____ is a major component in calcium-mediated adheren junctions. And what is the purpose of these junctions?
Classical cadherins
junctions between epithelial cells-locking them together
what are the 3 types of classical cadherins? and where are they found?
E-cadherin —- epithelial tissue
N-cadherin —- nerve cells
P-cadherin —- placenta
Desmocollins & Desmogleins, fall into what category?
Non-classical cadherins
Non-classical cadherins are found where?
Desmosomes
name the most common type of cadherin
E-cadherins
True or False: E-cadherins form tetramers via a RGD binding face
False:
form dimers via HVA binding face
T/F E-cadherins are found at the base of extracellular end of cadherin molecule
False: found at the tip
in E-cadherins, calcium binds to _____ ____ domains, and facilitate ___-homophilic dimers
4 extracellular domains
cis-homophilic
Loss of E-cadherins is associated with invasive behavior of ____ cells
tumor cells
what does HVA binding face stand for?
histidine-valine-alanine
____ are small proteins that link cytoplasmic end of a cadherin with cytoplasmic actin
catenins
T/F: Actin filaments act as skeletal structure in the extracellular matrix
false: intracellular matrix
How many forms are there of catenins? Name them
3 forms
beta & gamma are plakoglobin catenins
alpha catenin
____ form(s) of catenin bind to cytoplasmic end of a cadherin
beta & gamma
___ form(s) of catenin bind directly to cytoplasmic actin
alpha catenin
what is the major function/purpose of catenins?
Catenins serve as major interface between the cadherins that hold adjacent cells together, and the actin cytoskeletons of those cells
Selectins bind to carbohydrates, thus they belong to the ____ group
lectin group
Selectin binding site for _____ is located at the CRD, at the extracellular end of the Selectin. What does CRD stand for?
carbohydrates
carbohydrate-recognition domain
____ binding sites are also found near the CRD on selectins, and ____ is required for the binding of it
calcium
calcium
Define ‘extravasation’ and give another name for it
Movement of a cell from blood stream to tissue
transendothelial migration
____ are involved in the mvt of _______ from blood to tissues, this type of mvt is also called ________
Selectins, leukocytes, extravasation
or
transendothelial migration
Hey Arnold! TV show relates to the gross structure of which CAM?
Selectins
Name the 3 classes of Selectins and what they are associated with?
P-selectins —- platelets
E-selectins —- endothelial cells
L-selectins —- leukocytes
____ are glycoproteins that are mainly involved in cell-to-extracellular matrix interactions
Integrins
Integrins bind to both _____ matrix & _______
extracellular matrix & cytoskeleton
1 alpha subunit and 1 beta subunit make up _____
Integrin
Integrins bind to which two molecules in the extracellular matrix? What type of molecules are they?
Fibronectin & laminin
protein components of the basal lamina
T/F: Integrins interact with HVA sequences in fibronectin and entactin
False:
RGD sequence- Arg-Gly-Asp
in fibronectin and laminin
Laminin and Fibronectin interact with 3 molecules in the basement membrane…..name them
entactin, proteoglycans, collagen
Tonofilaments refer to ______
intermediate filaments such as keratin
In _______ integrins link the _____ domains of cells to the extracellular matrix via intracellular tonofilaments
hemidesmosomes
basal domains
Members of which family possess an extracellular segment with one or more folded domains, which is characteristic of ______?
immunoglobulin superfamily
immunoglobulins
_____ is a neutral adhesion molecule, and a member of what?
N-CAM
Ig Superfamily
mediate homophilic & heterophilic interactions
Name the 3 members of the Ig superfamily
N-CAM
I-CAM-1
I-CAM-2
Which member of the Ig superfamily facilitates transendothelial migration of leukocytes? And define this mvt…..
I-CAM-1
moving across endothelial barrier of blood vessel into the surrounding tissues
what are the three categories of junctional complexes?
adherens
occludens
gap junctions
this type of junction is associated with lateral domains, and is of the adheren variety. also associated with tonofilaments
desmosomes
this type of junction is associated with basal domains and with intracellular tonofilaments.
hemidesmosomes
tonofilament is another name for
intermediate filaments
explain the difference between zona adheren and zona occluden
adherens help adhere neighboring cells while occludens stop paracellular transport
zonulas imply what type of junction referring to their structure?
belt-like junction
surround the cell circumference
molecular complexes that anchor cells together and reinforce tissue integrity, found on basolateral domains
adherens
molecular complexes that create impermeable barriers to prevent paracellular transport, which helps to maintain concentration gradients
occludens
molecular pores that enable cells to quickly trade ions or small molecules to assist in cell to cell communication
gap junctions
differentiate between zonula and macula. are they associated with intracellular actin or tonofilaments?
zonula - complex travels all the way around the cell like a belt, intra cell actin. can be adheren or occluden
macula - spot or snap junctions, intra cell tonofilaments. are adheren only
anchoring junctions, with intercellular spaces filled with cadherin proteins: desmogleins & desmocollins
adherens
in adherens cadherin proteins are anchored to ______ plaques, which contain desmoplakin & _______
cytoplasmic plaques
plakoglobin
are desmogleins or desmocollins associated with the skin disease: pemphigus foliaceus?
desmogleins
zonula and macula adherens are mediated by interactions with _______
cadherins = desmocollins & desmogleins
anchoring junctions that connect the basal domain of epithelium to the basal lamina
hemidesmosomes
a hemidesmosome consists of: a ________ plate associated with ________ such as keratin. a _______ plaque linking the hemidesmosome to the basal lamina via filaments and ______.
cytoplasmic plate
tonofilaments
membrane plaque
integrins
a hemi/desmosome are which type of junction?
macula adherens
T/F: desmosomes link one cell to the basal lamina
false: hemidesmosomes link a cell to the basal lamina
desmos link cell to cell
claudins and occludins are ______ proteins, responsible for the _______ properties of the tight junction
transmembrane proteins
occlusive properties
these 2 proteins attach intracellularly to proteins ZO-2 and ZO-3
claudins
occludins
zonula occluden proteins facilitate interaction with the intracellular ______ filaments?
actin filaments
______ are spots that anchor the cell to the extracellular matrix via integrins and intracellularly to actin filaments.
focal adhesions
connexons are associated with ____ junctions
gap junctions
a gap junction allows cells to directly…..?
communicate with one another
how many subunits does a connexon have?
6 subunits called connexin - form a hexagon with a hollow center
a high concentration of what ion, causes gap junctions to close?
high calcium concentrations
