Extracellular Matrix and Proteoglycans- Reynolds Flashcards
What is the function of the ECM?
provides shape, lubrication, cushioning, anchoring, and allows communication
What is collagen and its structure?
it is the major protein component (30%)
left handed matrix as a single strand, right handed matrix as a triple strand
triple strand structure called tropocollagen
What is fibrillar collagen and where is it located?
It is a mixture of different overlapping collagen
Gives strength to skin, tendons, and ligaments
What is non-fibrillar collagen?
It interacts with fibrillar collagen and makes “mesh-like” structures
Where is collagen synthesized?
In the ER
How many amino acids are there in one turn of collagen protein?
3 amino acids (Gly-X-Y)
Usually X is a proline and Y is a hydroxyproline
disulfide linkages triggers the triple helix form
What is scurvy?
It is a vitamin C deficiency
Vitamin C is needed for synthesizing hydroxyproline in the collagen structure
What is Brittle Bone Disease?
Aka: osteogenesis imperfecta
Defect in type 1 collagen
usually from a point mutation
What is desmosine?
It is the 2D latticework that elastin creates that allows stretch
Where can you find elastin?
vessels, lungs, ligaments, and skin
What is fibronectin?
It is an ECM protein that acts as an anchor point
Has many different isomers
tissue specific
involved in cell adhesion, cell migration, embryonic morphogenesis, cytoskeleton, ECM organization
What are proteoglycans?
Proteins with large amounts of carbohydrates (GAGs)
Sugars are polyanionic because of uronic acid
Where are proteoglycans made?
Golgi complex
What are the functions of proteoglycans?
structural support, prevents compression in tissues, con interact to create aggregans, binds to numerous cations to neutralize, allows torsion and shock
As far as proteoglycans:
What is hyaluronic acid?
doesnt have a protein core or sufination
longest polysaccharide chain
component in vitreous and synovial fluid
As far as proteoglycans:
what is chondroitin sulfate?
most common GAG
major component of cartilage
As far as proteoglycans:
what is dermantan sulfate?
increases charge density
similar to chondroitin
As far as proteoglycans:
what is heparan sulfate?
most highly charged
major component of the basement membrane
binds to many soluble regulation proteins
As far as proteoglycans:
What is keratan sulfate?
most heterogenous
most diverse
What are MMPs? (matrix metalloproteases)
They digest structural components of ECM
Usually activated to remodel ECM
What is the structure of MMPs?
Depends on zinc (metalloprotease)
synthesized as a zymogen
abolished by EDTA
3 domains: propeptide, catalytic, haemopexin (which is sometimes absent)
How are MMPs activated and used?
propeptide domain must be removed
cysteine switch binds to zinc and prevents use by enzyme
The enzyme when activated uses the zinc molecule to activate water, which then can react with the amide bond of the protein substrate
What are integrins?
cell receptors linking ECM to cytoskeleton
dimer
What are cytokines?
they manage responses
include inflammatory responses like interleukins and interferons
can signal MMPs for remodeling
What are the four types of signaling in the ECM?
integrins, ionic changes, cytokines, GF
