CT 2 Flashcards
❂ Laminins
(basal laminae) (GP)
fibronectin
widely distributed GP
Collagens
most widely distributed protein in the body(GP)
Tf Glycoproteins have covalently-bound carbohydrate.
t Glycoproteins have covalently-bound carbohydrate.
the hydroxyl group ( -OH ) of serine or threonine • the hydroxyl group ( -OH ) of hydroxylysine
called “O-linked” in GP
(only in collagens)
hydroxylysine in GP
the amide group [-NH2] of asparagine -
called “N-linked”.
tf sugar residue Render glycoproteins more hydrophilic
t
sugar residues stabilize against —– and ——- binding to some components
Sugar stabilize against hydrolysis and modulate binding to some components
Linker Proteins
Fibronectins
Interlink collagens, proteoglycans with cell surface receptors
Fibronectins
Fibronectin
Enable cells to interact with the extracellular matrix
Adhesion ❂ Differentiation
Fibronectin purpose
Fibronectin purpose
Embryonic cell migration
Fibronectin Determine —-, ——- organization
Determine cell shape, cytoskeletal organization
Wound healing
Fibronectin
cancer cells lose the ability to synthesize ———
cancer cells lose the ability to synthesize fibronectin
In OC, fibronectin regulates
Dental mesenchyme differentiating into odontoblasts
Carbohydrate accounts for —– of the weight of fibronectin
5%
2 peptides connected in V like shape
Fibronectin
fibronectin —> 2 x 250 kDa chains linked by disulfide bond near the C-terminus.
2 x —– kDa chains linked by disulfide bond near the — -terminus.
Fibronectin
specialized domains for binding cell surface receptors and the extracellular matrix
links the outer components of the cell to the cell itself.
Fibronectin
RGD or RGDS
cell surface receptor-binding domain
disulfide bonds connect fibronectin at
C terminal
on the fibronectin structure which binding domain is most near N terminal
Heparin and Fibrin binding domain
binding domain next to cell surface receptor bidning domain and near N terminal
fibrin binding domain
fibrin heparin binding domain
most near c terminal of fibronectin (N to C)
cell surface receptor binding domain
contains RGD or RGDS
Laminin
linker proteins
Enable epithelial cells to interact with the extracellular matrix
Laminin
Laminin
high affinity for Type IV collagen
diff ,adhesion
Laminin
Embryonic nerve axonal outgrowth
Nerve regeneration after injury
laminin
Laminin in OC
contributing to terminal differentiation of ameloblasts and
in enamel matrix formation.
may also contribute to the growth of ameloblastomas
Laminin
Expression of α2 and β2 of laminin
in fetal oral squamous epithelium
α2 and β2 of laminin
Re-expression of these in adult oral squamous cell carcinomas
low Carbohydrate(13%)
Laminin
Laminin
Specialized domains bind cell surface receptors and the extracellular matrix i.e.
links outer components of the cell to the cell surface.
disulfide-linked heterotrimer
Laminin
α, β and γ chains
Laminin
cruciform shape
Laminin
Laminin molecules ——associate to form ——.
Laminin molecules self-associate to form aggregates.
For laminin
Nomenclature indicates chain composition
Laminin network formation involve
Ca
type 4 collagen and perlecan (extracelllar molecules)
bind laminin
integrin
bind laminin and fibronectin
binding site for the linker proteins
transmembrane proteins
and GP
integrin
The cytoplasmic side of integrins binds to —– components.
The extracellular domain of integrins binds to —– and —–
The cytoplasmic side of integrins binds to cytoskeletal components. ❂ The extracellular domain of integrins binds to fibronectins and laminins
binds ECM and transmembrane proteins
fibronectins and laminins
linker protein-mediated “communication”.
fibronectins and laminins
alpha beta subunit
integrin
tf
Cells can have 1 integrin receptors that link the cell to only one component of the extracellular matrix.
Cells can have multiple integrin receptors that link the cell to more than one component of the extracellular matrix.
The ——/—– sequence on the linker proteins binds specifically to the integrin receptors.
RGD/RGDS sequence on the linker proteins
Activation of integrins can lead to their — and —— of focal adhesions
Activation of integrins can lead to their clustering and formation of focal adhesions
C terminus of alpha and beta subunits of integrin
located in cytoplams
alpha subunit split into 2 segments
and linked together by disulfide linkage
disulfide rich repeats exist in
beta subunit of integrin
integrin binds to actin on
cytoskeleton side
out to in signal of integrin
ligand binds from ECM
Out to in signal in integrin
cell polarity
surviva;
proliferation
cytoskeletal structure
gene expression
Talin
involved in in to out signaling with integrin
cell migration
cell adhesion
ECM assembly
In to Out signaling with integrin
regulation of the extracellular binding activity of a cell’s integrins from within.
collagen
GP
Chemotaxis
Collagen
(major stress-bearing component
Colagen
Collagens form —– fibers with high —- strength; hold cells together in discrete units.
Collagens form insoluble fibers with high tensile strength; hold cells together in discrete units.
By weight, —- of the protein in vertebrates is collagen
By weight, 1/4 of the protein in vertebrates is collagen
cornea cartiledge
high percent collagen by weight
64 50
highest percent collagen by weight
skin 74
liver lung
small percent colagen by wieght
4 and 10
cOrtical Bone
aOrta
23%
10-24%
% collagen by wieght
after fibroblast make polypeptide system
OH and glycosylation occurs(collagen)
Secretion of procolllagen is followed by
hydrolysis of peptide bond to form tropocollagen
self assembly of tropocolagen to form
collagen fibers
crosslink in colagen fiber leads to
mature collagen fiber
tf collagen fber is made in between
procolagen and tropocollagen
F after tropocollagen
tf collagenis product of few genes
and few types
F over 40 genes
28 types
types 2 and 3 collagen
homotrimers
collagen 1,4,5
heterotrimers
polppetide in collegen
alpha
placenta skin
type 5 collagen
basment membrane
type 4 collagen
cartildge IVD
collagen 2
skin tendon
type 1 collagen
bone dentin
type 1 collagen
BV uterus reticular fibers
type 3 collagen
triple helical rod
collagen
Remarkably strong
Forms an insoluble fiber with high tensile strength
collagen
collagen
3000 Å long and 15 Å diameter
1/3 of the amino acids in collagen
Glycine
Proline
4-Hydroxyproline (Hyp)
3-Hydroxyproline (Hyp)
collagen
5-Hydroxylysine
collagen
tf collgen has Charged (—) amino acids
F
Charged (positive) amino acids
highest component in collagen and elastin
Gly
5 hydroxylysine
not present in elastin
present in collagn
desmosine and isodesmosine not in
collagen
collagen primary structure
glu X Y
X
Proline
Y
hydroxyproline
polar basic AA
also in collagen
X
proline
tf 3 hydroxylysine is in collagen
F
5 hydroxylysine
Y
hydroxyproline
secondary structure of collagen
tropocollagen with left handed helical structure
type 2 trans helix
2nd and tert structure of Collagen
quat structure
type 2 transhelix twist around each other to form right handed helix(superhelix)
triple helix of tropocollagen
has glycine in the middle
