COMPLEMENT me please Flashcards
Basic description of the complement system if u please
Front line of defence, evolved to be more sophisticated like my style NOT, interacts with other systems, ANCIENT, aberrant activation/deficiency = disease
What are the names of the three complement pathways?
Classical, alternative and lectin baby
Briefly describe the classical pathway
C1 binding to immune complexes, including antibodies and c-reactive protein ab dependent pathway
Briefly describe the alternative pathway
C3 binds to susceptible foreign surfaces eg bac and yeast cell walls
Briefly describe the lectin pathway
Lectin binding to carbs on microbial surfaces - ANCIENT
Define C1q
recognises and binds opsonins (antibodies and C reactive protein, which must be antigen bound for recognition.)
Where is the antibody binding site of C1q?
In the globular head
Where do non-immune activators of classical pathway bind?
The collagen-like tail. They also activate it.
Where is the CRP binding site?
In the collagen region. Maybe.
DRAW C1q + SERINE PROTEASES C1r and C1s
go girl g g go go go
What is ACRP30? And why, oh why, is it mentioned in the here and now?
An adipose specific protein in obese mice/human. Participates in energy homeostasis. It’s a homotrimer of beta-sandwich protomers, each of which has a 10 strand jelly roll folding topology, similar to TNF family. Mentioned because it is a module similar to the globular heads of C1q
What is collagen X NC1? And why is it mentioned?
Collagen X NC1 domain trimer, non collagenous. expressed in growth plate of long bones. C1q like C-terminal NC1 domain crucial for collagen X assembly. Mentioned b/c it is a module similar to the globular heads of C1q.
Name two modules similar to the globular heads of C1q
ACRP30 and Collagen X NC1
Describe the crystal structure of C1q trimer
Same fold as ACRP30 and Collagen X NC1 domain trimer. 3 distinct chains, A B and C. the differences in amino acids and structure probably reflect the different binding properties of each C1q chain.
NOW, ABOUT THE RECOGNITION PROPERTIES OF C1q. What kind of ‘imer’ is it? Describe the structure.
A heterotrimer. An overlay of subunits, strong conservation of beta strands and significant variability in loops. Different charged and hydrophobic residues on surface, could reflect specific individual recognition properties.
