Chapter 5: Antibody Structure & Effector Function Flashcards
Surface Ig
Embedded in B call membrane. Acts as BCR
Can transducer activation signals upon antigen binding
Each cell expresses multiple copies
Secreted Ig
Secreted by B cells (lacks extra c domain present in surface Ig)
Immunoglobulin structure (describe)
Two chains-heavy and light
Chains held together by disqualified binds
Chains have variable and constant regions
V=antigen binding
C= effector function
CDR
Complemantarity Determining Regions or hypervariable regions
3 on each variable region
Contains most of the variability, mostly in CDR3 (due to vj/vdj joining)
CDR1 and 2 Germline encoded, not 3 because it is due to joining/rearrangement
Types of light chains (Ig)
Kappa and lamba.
Same type of light chain is found on both arms
Types of heavy chains (Ig)
Type determines isotope/effector function
5 types
IgG
Monomer (bivalent)
Major class in secondary response
Large hinge region (flexible arms)
High affinity
IgM
Has extra C domain (surface Ig)
Pentamer
High avidity and low affinity
Oligomerization by J chain
IgA
Dimer (tetravalent)
Major Ig secreted in GI and respiratory tracts
Oligomerization by J chain
Uses secretory component for trancytosis into luminal space
IgD
Low abundance
Mainly cell associated
IgE
Involved in allergic reactions
Involved in response to parasites
Binds to mast cells and induced degranulation
Has extra C domain
Affinity
The strength of binding of one molecule to another at a single site
Avidity
Sum total of the strength of binding between two molecules or cells to one another (where multiple binding sites are involved)
Antibody effector functions: direct
Involves antigen recognition of Fab part of Ig
Antibody effector functions: indirect
“Targeting mechanism”
Involves Fc part of Ig
