Ab Structure and Function

Question 1

IgG

Answer 1

Most common Ig and has widest range of functions
Predominant class in SERUM
Toxin neutralizing, agglutinating, opsonizing, bacteriolytic
Interchain disulfide bonds btween same residues

Question 2

IgM

Answer 2

Most primitive Ig and is the most potent at complement fixation but is unable to directly mediate many functions such as opsonization or ADCC
Predominant class in PRIMARY IMMUNE RESPONSE
Pentameric - J-chain

Question 3

IgA

Answer 3

Predominant class in SECRETIONS
Agglutinating, opsonizing
Found as monomer, dimer, trimer
-one of which is secreted --> contains a secretory piece that inhibits degradation
-J-chain

Question 4

IgE

Answer 4

Associated with immune response of parasites and is imp in the allergic reaction
Fixes to mast cells

Question 5

IgD

Answer 5

Located on surface of human IMMATURE B-CELLS

Co-expressed with IgM on surface of B-cells

Question 6

Parts of Ab

Answer 6

Fab–> ability to bind to Ag

Fc–> part that binds to cells

Question 7

Variable Region

Answer 7

Variable - contains A.A seq coding for the Ag binding site

Question 8

Hypervariable Regions

Answer 8

Parts in variable region that have a great deal of variability - provides seq of very specific Ag binding site

Question 9

Variable Region - Heavy and Light Chains

Answer 9

Contain 3 hypervariable regions each - although far a part in primary seq are close together in the Ag-binding site