6. Complement proteins Flashcards
Non specific humoral factors that consist of complex series of more than 30 soluble and cell bound proteins
Complement proteins
What is the main function of complement proteins?
Eliminates or destroy cells that triggers complement activation
Who coined complement?
Paul Ehrlich
Who elucidated the function of complement proteins?
Jules bordet
What are the major fraction for complement protein?
Beta 1 and beta 2 globulin
How complement proteins eliminated cells?
Lysis
How many major complement proteins?
9 (C1 - C9)
What is the sequence for the Classical pathway?
C1, C4, C2, C3, C5, C6, C7, C8, C9
How is peptide chain being assigned with what language?
Greek Letter (Gamma greek sign)
How is peptide chain being assigned with what language?
Greek Letter (Gamma greek sign)
C3:
C3 alpha
C3 Beta
C3 Gamma
Activated complement proteins are assigned in _________ letters
Lower case
Ex:
C3a
C3b
What is the end result for classical pathway?
Lysis of foreign cells
What are the 3 recognition unit for classical pathway?
C1q
C1r
C1s
(Tri molecular complex)
Largest C protein which initiates C activation by binding to 2 adjacent Fc portion of an antigen-bound IgM or IgG
Like a Docking site
C1q
Activation Relys on in the presence of immune complex (IgM or IgG)
Immune complex dependent
What immunoglobulin is the best complement activator?
IgM
because of pentameric
IgG on the otherhand need 2 to have 2 Fc
Recognition unit for proteolytic zymogen
C1r
Recognition unit that is a
zymogen when free,
esterase when bound
Responsible for cleaving or activating the next complement protein
C1s
Tri molecular complex is held together by?
Calcium ions
Ca2+
Activation units what is the 1st activation
C4
Function of C4?
Activates C1s to cleaves C4alpha
What is the resulting fragments?
C4a and C4b
What is C4a?
This triggers inflammatory cells causing degranulation such as histamine
anaphylatoxin
what is C4b?
Attaches to cell membrane
(of foreign cells)
NOTE: C4 composed 3 peptides (Alpha, Beta, Gamma)
What is the 2nd activation unit?
This binds to C4b and is cleaved
C2
C2 is activated by?
C1s
What is the resulting fragments for C2?
C2a, and C2b
remains w/ C4b w/c forms ____________ or ___________
C4b2a or C3 convertase
C3 convertase was made in the presence of?
Magnesium
Most abundant complement protein in serum which serves as the merging point of the activation pathway which lead to common pathway?
Secreted by macrophages
C3
C3 is cleaved by?
C3 convertase
What are the resulting fragments of C3?
C3a and C3b
What is the function C3a?
anaphylatoxin
What is the function of C3b?
Binds to C42a to form C4b2a3b (C5 convertase)
Can act to opsonins independently?
C3b
1st membrane attack unit?
C5
What are the resulting fragment for C5?
C5a and C5b
Resulting fragments of C5 that serves as a chemoattractant or chemotactic factor and anaphylatoxin
C5a
Attracts the migration of phagocytes
Chemotactic factor
Resulting in fragments of C5 that attaches to cell surface
Docks for membrane attack units (Susunod an proteins)
C5b
2nd and the 3rd membrane attack unit respectively
C6 and C7
Attaches to C5b to form the first membrane attack complex which is?
C5b67
Inserted to the cell membrane creating pores or erosions
C8 and C9
When C8 attaches to C5b67?
slow lysis
What happen when C9 attaches?
C5b6789 = fast lysis
