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Cell Adhesion
junctions
ocluding / tight junctions
created through integral protiens:
occludin + occludin
claudin + claudin
create barrier to prevent entrance of anything between cells = paracellular diffusion barrier
"cap"
cadherin related
(zonula) adherens (aka belt desmosomes)
"seem"
(spot) desmosomes (aka Macula adherens)
"reinforcement"
gap junction
6 connexins create a connexon
2 connexon of adjacent cells adhere to form gap
purpose: action potential and Ca pass through
can be open or closed
hemidesmosomes
Basement membrane
connects epithelial tissue to connective tissue
2 sections
basal lamina
made of
laminim
type 4 collagen
protoglycans
reticular lamina
made of
collagen
integrin hooks epithileal tissue to basement membrane laminim in basal lamina
additional connective tissue basil to reticular to main connective tissue
Definition
attachment of cells to each other to create tissues
Principals
cell adhesion molecules (CAM) in membrane
cadherins
ligand: cadherins
Ca++ dependent
connects epithelial and muscle cells
at cell jucntions
(zonula) adherens (aka belt desmosomes)
cadherins are arranged in strips on sides
catenins link (are combining component) of cadherins to actin of cytoskeletinÂ
enables vibrations in one cell to be felt in other
plaque (a peripheral protein) cements cadherins to cell wall from with in
(spot) desmosomes (aka Macula adherens)
plaque anchors each cadherins to cell wall from with in
plaque has keratin filaments to further anchor in cell directly
spot reinforcement of zonula adherens
E-cadherin to E-cadherin
E- (for epithileal), N- (for nerves), P- (platelets and epithilelal)
always two together = dimer
connected by calcium bond to each other at binding site
on dimer connects to other dimer via calcium bond at binding sites
homophilic interaction (cadherin + cadherin)
purpose: create permanent sheets of epithelium
selectins
ligand: polysaccharide
designed to glycoproteins of another cell
Ca++ dependent
CRD - Carbohydate Recognition Domain = Binding site of selectins turned on by calcium
types
L-Selectin (Leukocytes)
to E-Selecting
E-Selecting (Epithelium)
to L-Selectin
 P-Selectin (Platelets)
to Mucins (PSGL-1)
purpose: to connect temporary WBC with Epithelial cells of blood vessel wall
also with integrin to Ig-CAM at same time
integrins
ligand: fibromnectin, laminin, fibrinogen, ig-cam
not dependant on Ca++
actions
binds cell to matrix in connective tissue
connects to cytoskeletin
know integrins on pg 515
LFA-1
connected to ig-CAMs (between white blood cells and endothelial cells)
MAC-1
connected to ig-CAMs (between white blood cells and endothelial cells)
Laminin
cell matrix connection
Fibronectin
cell matrix connection
(GPIIb/GPIIIa) Fibrinogen
platelet aggregations
has alpha and beta sub unit
linked by various proteins to actin of cytoskeletin
immunoglobulins
ligand: other CAM
not dependant on Ca++
know
ICAM-1
intercellular
ICAM-2
VCAM-1
vascular
NCAM-1
neuro
CD4
in T4 cells - helpers
CD8
T-attack / suppressor cells
prupose: white blood cell interaction with endothelium (simple squamus style) cells
all our integral membrane proteins
CAM associated to a ligand
cell controls adhesion
through surface density of CAMs
state of agregation
to move next to other cell
state of activiation
to turn on CAMs
Rate of ligand binding and association
CAMs interact with cytoskeletin of cell
for movement
CAM + Ligan can activate cellular intracellular signal transduction pathways | 
