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25 Cards in this Set
- Front
- Back
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Keratan Sulphate (KS)
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poly-N-acetyllactosamine chain
Galβ1-4GlcNAcβ1-3 |
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KSI
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cornea
N-linked core glycan structure ~50 diasaccharides |
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KSII
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skeletal
O-linked via GalNAc ~5-10 diasaccharides |
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KS modifications
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sulphation (mono/di)
fucose sialic acid fewer glycosyltransferases/sulphotransferases that CS/HS |
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Small Leucine Rich PG (SLRP)
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20-30 aas
β sheet parallel to a helix a/β horseshoe fold sub-family of LRR family |
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SLRP Class I
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DS/CS @ N terminal
Leu Rich Repeats (LRR) N-linked glycans on LRR |
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SLRP Class II
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Tyrosine sulphate at N-terminal
LRRs N-linked KSI at LRR |
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Decorin
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class I SLPR
one CS/DC chain Binds collagen modulates TGFβ activity forms dimers |
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SLRP subfamilies
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based on:
gene organisation aa similarity no of LRRs spacing of Cys in N-terminal segment |
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SLRP expression patterns
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vary in level of expression and modifications from tissue to tissue
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SLRP function
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many bind to collagen and regulate fibrillogenesis
decorin biglycan fibromodulin lumican |
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collagen fibril give _____ _____ to tissues
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tensile strength
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Decorin binds to collagen ____ _ containing fibrils
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type I
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Lumican binds to collagen ____ _ containing fibrils in the ______
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type I
cornea * regular arrangement of fibrils and spacing important for TRANSPARANCY |
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SLRP function - can bind ___/cytokines/_______ and modulate their function
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GFs
morphogens e.g collagen bound decorin / biglycan / fibromodulin can bind TGFβ biglycan binds BMPs |
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SLRPs can bind ______ _______ and control cell proliferation
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cellular receptors
e.g decorin binds EGFR and antogonises R Tyr phosphorylation |
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SLRP functions often depend of ______ & GAG components
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protein
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Decorin KO mouse
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highly fragile skin - reduced tensile strength and thinner dermis
disrupted collagen fibril formation ~ to Ehlers-Danlos Syndrome (EDS) in humans |
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Lumican KO mouse
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develop corneal opacity with age
also develop eds-like skin laxity KS content reduced by 25% |
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compensation between SLRPs
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Increased lumincan in tendon of firbromodulin KO mice
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decorin & biglycan double KO -->
v.severe v. _______ ____ collagen fibres |
irregular shaped
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Macular Corneal Dystrophy (MCD)
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autosomal recessive
progressive corneal haze from early age ---> loss of vision cause -> truncating mutations in CHST6 (carbohydrate sulfotransferase 6) SHST6 catalyses addition of S to KS chains complete loss of highly sulphated KS in cornea |
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Detection of sulphated/non sulphated KS by _________ EM
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immunogold
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in KS
loss of 6-O-_______ on GalNAc affects _-_-_______ of ____ & chain elongation |
sulphation
6-O-sulphation Gal |
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Pathogens can _____ SLRP CS/DS
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utilize
e.g Lyme disease agent uses DS on decorin to bind and be retained in ECM of dermis |
