Collagen Flashcards
3 main tissues in connective tissues
- collagen
- elastin
- proteoglycans
3 main properties of collagens
- tensile strength
- compression resistance
- specialized networks
what is at ends of collagens
registration peptides
featuure of collagen chain
Gly-X-Y
What allows 3 helix structure
registration peptides @ C-terminal + Gly/x/y repeat
what keeps strand together after peptides cleaved off
H-bond > tropocollagen
what links 2 triple chains
lysine and hydroxylysine covalent crosslinks
what a group of many chains together create
quarter stagger array
3 types of collagen fiber org. and their locations
- unidirectional - tendon
- random - skin
- orthoganal - cornea
what happens if don’t convert proline to hydroproline
no H-bonds - loose joints, teeth fall out, weak bones - scurvy
what is needed to convert proline to hydroxyproline
Fe - vit C
what happens if don’t convert lysine to hydroxylisine (lacking Vit. C)
Ehlers Daniels Type 6
- super extensible skin, joint laxity, detached lenses
what happens if fail to remove N-registration peptide
Ehlers Daniels Type 7
- interferes with collagen fiber packing
- skin brittle, congenital dislocations
what happens if fail to form lysine/hydroxylisine cross-link
cutis laxa - decreased crosslinking - loose floppy skin - sharpei
causes of fail to form lysine/hydroxylisine cross-link
defects in copper metbolism
2 major types of genetic collagen
- continuous - types 1,2,3
2. discontinuous - types 4
locations of Type 1 collagen
skin, bone, tendon, ligament
locations of Type 2 collagen
cartilage, cornea,
locations of Type 3 collagen
fetal skin, vasuclar tissues
locations of Type 4 collagen
basement membrane
feature of discontinuous collagen
registration peptide not removed
cause of chondroplasias
mutations in type 2,9,10,11
consequences of chondroplasia
malformations in articular cart
joint deformities
familial osteoartritis
what happens for mutations in type 3 coll.
EDS type 4 - most severe phenotype
- thin translucent skin
- fragile blood vessels
what happens for mutations in type 4 coll.
Alport syndrome - def. in basement membrane
- glomerulnephritis, kidney failure
- hearing loss
what happens for mutations in type 7 coll.
dystrophic epidermolysis
- failure of demis to anchor
- severe blistering of skin to minor trauma
what happens for mutations in type 1 coll.
osteogenisis imperfecta
- bone fragility, blue sclera, hearing loss
cause of osteogenisis imperfecta (2)
- silent allele causes deletion so one of the 3 triple helix strands to not form
- point mutation - Gly to Cys - kinks triple chain
chances of mutation in osteogenisis imperfecta based on allele?
a2 - 1/2 messed up (choose once)
a1 - 3/4 messed up (choose twice)
Important chars. of elastin
- single gene
- don’t lay more down
- mechanical durability
changes in dist. of elastin vs. collagen
as go from aortic arch down becomes less elastic
what is structure of tropoelastin
alternating hydrophobic and crosslinking domains
3 basic layers of aorta
- intimal
- medial
- adventitial
what part unravels when elastin pulled
hydrophobic domains - refold in polar H2O
consequences of supravalvular aortic stenosis
- narrowing of arterial vessels
cause of supravalvular aortic stenosis
- frameshift mutations, translocations - one allele doesn’t function
- 1/2 the elastin
- gene/dose effect
consequences of williams-beuren
- SVAS is common
- cocktail personality
causes of williams-beuren
- large deletion of chrom 7
consequences of cutis laxa
- loose saggy skin
causes of cutis laxa
- frameshift mutation near c-term
- disordered, fragmented elastics
probs from hypertension
- vessel deposits extra elastin due to pressure which fills in vessel
causes of arteriosclerosis
- elastic lamina fragments
- smooth muscle migrated to intimal layer
- thickening of intimal layer causes plaque
causes of emphysema
breakdown of elastin in alveoli
what does elastin form on
scafolding of microfibrils
causes of marfans
defects in fibrillin-1 > can’t make microfibrils
features of proteoglycans
- viscous
- resist compression
- regulate macromolecule diffusion
- bind and trap cations
basic structure of proteoglycans
protein core with attached glycosaminoglycan
- form bottlebrush shape of core of hyaluronic acid
causes of lysosomal storage diseases
- don’t have enzymes to break down proteoglycans
- they build up in lysosomes
cause of hurler’s syndrome
- don’t have specific enzyme (iduronidase)
consequences of hurler’s
- accumulate heparin sulfates
- progressive cell, tissue, organ damage
- corneal clouding
- severe mental retardation
function of fibronectin and laminin (3)
- link matrix to matrix and cells
- organize matrix
- outside-in signalling
