Immunoglobulin Structure and Function Flashcards
what are two forms of antibodies
membrane bound
Secreted
antibodies are found on the surface of what cell and function as what
B - cells
B-cell receptors
Secrete antibodies bind what
antigens
what are 3 functions of secreted antibodies
neutralize toxins
prevent entry and spread of pathogen
eliminate microbes
Proteolytic cleavage of antibodies by papain creates what structures
Fc - determines function
Fab - determines recognition, 2 separate pieces
what is labelling on Fab fragment
single antigenic binding region
Proteolytic cleavage by pepsin creates what structures
F(ab’)2
pFc’ (one piece)
what makes antibodies flexable
hinge region
what is the role of the constant region of the antibody
imparts function of antibody to molecule
is there genetic variation in constant region
little
affinity
strength of binding b/w single Ab arm and Ag epitope
affinity is expressed how
dissociation constant (Kd)
avidity
overall strength of attachment of Ab and antigen
Immunoglobin molecule consists of what
2 identical heavy chains
2 identical light chains
Domain
in both H and L
110 amino acid residues
Light chain consists of what two domains
constant (C) domain
variable (V) domain
What region is located on the variable domain of the light chain
complementarity determining regions (CDR)
hypervariable region
What domains does Heavy chain have
variable domain
several constant domains
within the variable domain the heavy chain has what
3 CDRs or hypervariable regions
antigen binding occurs with what domains
Variable heavy
variable light
how do the CDR regions of antibody form antigen combining site
folding of Heavy and Light chains
Where is hinge region found
Heavy chain
isotypes
5 types of immunoglobulins (antibody) based off of Heavy chain constant regoin
what are the 2 types of Light chains based on their constant region
kappa
lambda
Is there a difference in function for kappa and lambda
no
within a single immnoglobulin molecule how many types of light chains are present
one
either 2 kappa or 2 lambda
do the isotopes have different chemical properties like molecular weight and half life?
yes
what are 4 functions of isotypes
receptor
neutralize/block activity
Ag-Ab complex recognition via Fc receptors
serum complement activation
agglutination of isotypes
process of neutralization can occur in solution or on surface of cell
the process of agglutination does what to the cell
phagocytized or removed from circulation
opsonization of isotypes?
coating surface with antibody
the classical pathway for complement uses what for starting point
antibody
phagocytosis or removal of antibody bound material happens through what
receptor mediated event on the phagocyte (FcR)
special function of IgA
cross mucosal epithelial membrane via Poly Ig receptor
special function of IgE
coat mast cells allowing release of their granules upon allergen binding
special function of IgG
sensitize NK cells and eosinophils via FCR
which immunoglobin has the highest concentration of serum of normal individuals
IgG
what are the polymeric antibodies
IgM
IgA
how are polymeric antibodies stablized
J chain
in antibody maturation, IgM changes to
IgG
In order for IgM to change to IgG what must happen in recognition of antigen
recognition of same antigen from primary to secondary response
what defines an isotype
epitopes on constant region
no variation by member of same species
Allotype defined by
epitopes on constant region
show variation by members of same species
idiotype
epitopes on variable region
show variation within same individual
xeogeneic
non human
chimeric
66% human
humanized
90-95% human
fully humanized
human
