ECM/Cell Junctions Flashcards
the ECM is a complex network of ____ in the extracellular space
macromolecules
the ECM is secreted by:
the cells in which inhabit it
the ECM is a substantial contributor to ____
tissue volume
ECM gives ____ and ____ support to cells and tissues
structural; organizational
the ECM regulates cellular processes like ___, ____, and ____
proliferation; differentiation; migration
4 main families of molecules comprise the ECM
- collagens
- elastins
- glycoproteins
- proteogycans
collagen molecules are a ____ composed of 3 ____ chains
triple helix; polypeptide
each polypeptide chain of collagen is itself ____
helical
collagens have a characteristic repeating sequence of ____
Gly-X-Y
intra and inter chain helices of collagen are stabilized by ____
H bonding
collagen is ___ of total body protein, ___ of it is ____
30% ; 90% ; type I collagen
defective type I collagen causes _____
osteogenesis/dentogenesis imperfecta
genetic defects cause the ____ in the collagen chain to be replaced by other amino acids; collagen chains cannot fold correctly into ____; the resulting ____ are defective
glycine; triple helices; collagen fibrils
type ___ collagen forms a matrix
IV
type IV collagen associates with ____ collagens, forming a mesh-like structure
fibrillar
type IV collagen is a major structural component of ____, _____, and _____
basement membranes; vascular walls; the glomerulus
anomalies in type IV collagen in the glomerulus cause disease:
Goodpasture’s syndrome- autoimmune disease
Alport syndrome- defective type IV collagen chains
elastins provide ____ and ____ and are the dominant ECM protein in ____
flexibility; resilience; blood vessels
elastins are abundant in ____, ____, and ____
skin; lungs; intestines
elastins are stabilized by ____ crosslinks; crosslinks contains ____
two-way; desmosine
types of glycoproteins:
fibronectin; laminin
there are at least 20 types of fibronectin, with ___ and ____ forms
soluble; insoluble
fibronectin is produced by ____ of a single precursor ____
alternative splicing; mRNA
alternative splicing controlled by many factors and processes:
- tissue or cell of origin
- embryogenesis
- wound healing
- oncogenesis
fibronectin facilitates communication between intracellular and extracellular compartments, important for:
cell adhesion, growth, migration, differentiation, embryogenesis, and wound healing
loss of fibronectin from the surface of ____ may help initiate ____
tumor cells; metastasis
fibronectin binds to ___ molecules on cells
integrin
soluble fibronectin in saliva prevents ____, _____, and other oral pathogens from binding to the oral cavity
streptococcus mutans; porphyromonas gingivalis
laminin is vital for ____ and ____; laminin is an integral part of the ____
tissue maintenance; survival; ECM scaffolding
defective laminins can causes diseases:
- muscular dystrophies
- lethal skin blistering disease, epidermolysis bullosa
- defects of kidney filter
laminin found primarily in ____, gives ____ support to the ECM
basal lamina; structural
laminin is the major component of basement membranes in ____ and ____ tissues
epithelial; muscle
laminin binds to cells, often through the ____ family of proteins
integrin
epithelium attaches to implants by a longer ____ as compared with a natural tooth
junctional peri-implant epithelium
proteoglycans combine to form ____
aggrecan
in the cartilage matrix, individual proteoglycans are linked to a nonsulfated GAG, called ____, to form a giant complex with a molecular mass of about 3 million
hyaluronic acid
functions of proteoglycans
- structural support
- gel formation due to hydration
- tissue-specific functions
tissue specific functions of proteoglycans
- bind growth factors
- regulate the activity of specific proteins (regulate enzyme activity)
- act as co-receptors
proteoglycans have many ____ charges, which attract ____ and ____
negative; cations; water
the negative charges of proteoglycans result in ____ of the ECM, which provides ____ and ____
hydration; rigidity; durability
proteoglycans are < 10% of ECM protein, but because of their ____, ____ fill most of the extracellular space
hydrophilicity; GAG chains
