Lecture 12 - Other Roles Of Proteoglycans Flashcards
(46 cards)
What do proteoglycans allow?
They are adhesion molecules and allow cells to differentiate between self and non-self
In what organisms are cell surface proteoglycans used?
In simpler organisms
What are metazoans (sponges)?
They are the simplest multicellular organism and there are 3 types
What are the 3 types of metazoans?
Microciona prolifera, Halichondria Panicea and cliona celata
What is interesting about metazonas?
They can recognise their brother and sister cells even when reformed - don’t form hybrids
What happens if you remove the cell surface proteoglycans from the metazoans?
It abolish the effect of recognising brother or sister cells
What are the removable proteoglycans called to abolish the effect on metazoans?
Glyconectins
What do proteoglycans appear to act as?
Like enzymes, there is evidence that they are able to act as a receptor like protein tyrosine phosphatase
What is 6B4 proteoglycan?
It is a major soluble CS-PG in the brain and can be removed by PBS (phosphate buffer saline) and is then solubilised
What are two types of neurons that are examined from the cerebral cortex and the thalamus when looking at 6B4 proteoglycan (phosphocan)?
Cortical and thalamic neurones
Does 6B4 proteoglycan have anything to do with cell adhesion?
Coated a well with poly-l-lysine which cells cells adhere. Put in islands of 6B4 and the cells stuck to the plates with no 6B4 but with 6B4 no cells attached even with poly-l-lysine
6B4 is a ……
Anti adhesion molecule
What is neuritis extension?
Neurone throwing out protections - starting to form neurones
What type of neurone shows neurite extension?
Cortical neurones not thalamic
What is the structure like of 6B4 chain?
It has an N and C terminal, N terminal seems to be like carbonic anhydrase. At the C terminal there are chondroite sulphates found.
What does it mean if Cs chains are attached?
That the composition is glycine and serine rich
Why is serine important?
As it has an OG group that the GAG chain attaches to
What is glycine important?
Because it is small so it allows for a lot of packing of the GAG chains
What is chondroitinase ABC?
An enzyme that chews off the chondroitin sulphate chains - it has no effect on neurite extension
What can abolish neurite extension?
If an antibody attaches to the N terminal where the carbonic anhydrase like region is - it abolishes the neurite extension
What does chondroitinase digestion abolish?
The repulsive effects, the C terminal is the repulsive effect
The more 6B4 proteoglycan = the more
Neurite extension - it is concentration dependent of 6B4
What does 6B4 modulate?
It modulates morphogenesis and differentiates neurones depending on its spatiotemporal distribution and the cell type in the brain
What is found under the N terminal (carbonic anhydrase like region)? Of phosphocan
A fibronectin like repeat
