Lectin pathway to OZ Flashcards
What can MBP activate? And in what order?
Complement. C4-C2-C3.
How does MBP recognise carbs?
via cell surface oligosaccharide structures. recognition occurs via CRDs of the collectins. It is calcium dependent, occurs at Ca2+ site.
Which three complement components have very similar structures?
MBP, HSP-D and RSP-A
What is HSP-D
Human Lung Surfactant Protein D. The first line of defence against airborne pathogens. Recognises lots of carbs on surface of lung pathogens but not host cell surfaces.
How does HSP-D interact w/immune cells?
Presents bound pathogens, but will only when 2/3 bind simultaneously, thus dependent on a matching arrangement of carb binding sites on surface of invading organisms. USES CRDS TO BIND PATHOGENS.
What is HSP-D import in?
Non-self recognition
Draw HSP-D
4 trimers. X shaped structure.
What does HSP-D modulate?
Allergic reactions, by binding glycosylated allergens.
What is the biomedical significance of HSP-D?
Mouse SP-D neutralizes influenza. There is a correlation between HSP-D polymorphism and susceptibility to pneumoniae in humans. AND a deficiency of hSP-D and A in cystic fibrosis cases.
MALTOSE BOUND HSP-D. Wat is it.
A carb-bound HSP-D
What happens to the binding pocked of HSP-D when bound with maltose?
Little to nothing, contact between carb and protein is limited, h-bonding interactions between sugar ring hydroxyls and bound Ca ion.
MALTOTRIOSE BOUND HSP-D Wat is it
Another carb bound HSP-D
What is the structural mechanism around maltotriose binding?
Orientation of Glc-1 essentially same as in Maltose binding, but Maltotriose has three subunits (hence the TRIose) and Glc3 is aligned slightly offset with the ring of Phe335 and therefore the plane is deflected 90degrees in comparison to Glc1. Get that motherfucker? I’ll give you a fucking date if you do.
What is significant about other ligand bound HSP-D structures?
They are numerous and boring, all show interactions verrry similar to Glc3 and 4 hydroxyls
SELF VS NON SELF HSPD RECOGNITION SHENANIGANS?
The distinguishment occurs because of the spacing of the CRDs relative to the carbohydrates on the molecules favours bacterials rather than self.
