2 IG structure Flashcards
what is b cell receptor
antibody
will not go from membrane bound to soluble BCR unless
you get infection
specificity of epitope on BCR will not change when it is
soluble
every antibody has how many antigen binding site
2
what are two functional roles of b cell receptor
looks for antigen
secretes antibody
immunoglobulin is
antibody
Ab or Ig means
antibody
neutralizing antibodies
bind microbe or toxin and block them from entry
enhance innate cell function how
complement with antibody works better
what is big difference b/w BCR on surface of receptor and the secreted form
there is transmembrane region that will not be present in secreted form of antibody
BCR with transmembrane region will
stay on surface of b cell ,will be BCR
what is basic structure of antibody
heavy chain and light chain
antibody contains how many heavy and light chains
two identical light chains
two identical heavy chains
variable region on antibody is involved in
binding to antigen
constant region of antibody is involved in
mediating effector functions
antigen binding site of antibody is combinatino of
variable region of heavy and light chain - so they will both contribute to antigen binding site
resting b cell what will happen to most of them
they live until they die and they never find their “partner”
mature naive b cell must express what on surface
must express both IgM and IgD on surface
domain within light chain
constant and variable domain
domain within heavy chain
3 or 4 constant domains and 1 variable domain
Fab
portion that is antigen binding on antibody
Fc
portion that is constant on antibody
heavy chain has how many constant regions
3
light chain has how many constant regions
1
each domain in antibody is
immunoglobulin domain
connecting Fc to Fab fragment
hinge region
hinge region
antibody is flexible, hinge connects Fc to Fab fragments
what does hinge flexibilty allow
antibody to bind antigen close together, far apart, moving
antibodies recognize almost how many antigenic determinants
infinite number
what portion recognizes the antigen
variable region
hypervariable region
determines specificity within variable domain
CDR stands for
complementarity determining region
what is magic number for CDR
3
there are how many hypervariable regions
3
how many hypervariable chains in heavy and light chain
3 in each
what region has the variablity in antibody
v region
what type of interaction does epitope have with zika virus
electrostatic forces hydrogen bonds van der waals forces hydrophobic forces NOT covalent
epitope does not have what kind of bond with antigen
no covalent bond
dissociation constant of 10^-12 is what affinity
very strong
dissociation constant of 10^-4 is what affinity
relatively weak but still have interaction
even though no covalent bond b/w antigen and antibody, it is still
a very strong bond b/c of all the forces
avidity
one single interaction of one antigen binding site with one epitope on
one that binds two is stronger than one that binds two.
avidity is combination of all the different interactions
once an antibody binds a particular pathogen what does it do
complement system more efficiently activated. C1 can bind directly to antibody molecule - the Fc region
IgM is a
pentimer
IgM has how many binding site
10
if a b cell is ready for action (to mature) it will have how many different antibodies on surface
2
IgM and IgD
isotype switching only happens
after infection
describe clonal selection with IgM and IgG
our body already has antibodies for things that will help get rid of diseases we’ve never seen
What are the major classes of immunoglobulin
IgG M D A E
Fc is made up of
heavy chain
heavy chain designated by
greek letter
gamma heavy chain will make
IgG
u heavy chain will make
IgM
delta heavy chain makes
IgD
alpha heavy chain makes
IgA
epsilon heavy chain makes up
IgE
how many constant domains are in IgE
four
how many constant domains are in IgM
four
how many constant domains in IgA
three
what are the only immunoglobulins that have four constant regions
IgM
IgE
what are first BCR
IgM
IgD
breast milk has what immunoglobulin
IgA
IgE closely linked with/role in
parasite infections
allergic diseases
what is main antibody in blood
IgG
IgG can cross
placenta
what is most abundant antibody
IgG
when you first get sick what is main antibody
IgM
IgM is a
pentamer
what is marker for B cell to be mature
IgM
what is only real function of IgD
present on surface of B cell
if IgD onsurface of B cell
B cell is mature - will respond if it encounters antigen
IgA is in
saliva, tears, breast milk, in secretions/mucosal surfaces
IgE
parasites
allergic responses
what antibody for parasites and allergic resposnes
IgE
IgE is how much in blood
very low concentrations
what is biggest antibody
IgM
IgG and IgA have
subtypes
IgG types
1, 2, 3, 4
IgA types
1, 2
very very small amounts of
IgE
when is IgM pentamer
only when secreted. when it’s on surface of B cell it is a monomer.
IgA is a (shape)
dimer
Besides IgM and IgA they are all
monomers
how is pentomer made
J chain
greek ltter for heavy chain for IgM
u (mu)
IgM can turn on what pathway
complement - classical pathway (only one to turn it on)
monomeric IgM has what kind of affinity
low
pentamerica IgM has what affinity
high avidity
80% of all antibodies in blood is
IgG
what is heavy chain of IgG
gamma
IgG can turn on what pathway
complement - classical pathway (needs two to turn it on)
memory b cells will have what in surface
mIgG
memory b cell is going to be mainly what antibody
IgG
FcRn is
brambell receptor or neonatal Fc Receptor
endothelial cells surrounding baby - how does IgG go to fetus
IgG attached to FcRB present in moms blood -endocytoesed through Fc Receptor and then released to baby
what type of protection is it when mom passes IgG to baby
passive protection - baby got premade IgG
what is another passive protection
antibody - like if you’re bit by a snake
If IgA is in serum it is a
monomer
if IgA not in serum it is a
dimer
What holds together two IgA
J chain
Dimeric IgA connected by
J chain
IgA is main antibody secreted on
mucosal surfaces
how does IgA get to baby
poly-Lg receptor
the receptor uses J chain to bind the dimer, endocytosed, the Poly-Ig goes with the IgA (different than the other IgG)
parasites and allergies, what antibody
IgE
what is receptor for IgE
Cell-bound via FcR
epsiolon is the box
what is the affinity of IgE to Fc receptor
very high - when it binds it is staying
IgE receptors expressed on what cells with high affinity for binding to IgE
mast cells,eosinophils, basophils, langerhans cells
why id IgE very low in blood
it binds to mast cells then just stays bound to them
high affinity FcepsilonR binds IgE in the absence of
antigen
IgD found where
on mature b cell
IgD is co-expressed with
IgM on mature B cell
describe IgD and IgM and RNA splicing
IgD or IgM is decided based upon RNA splicing - so it’s not until during the RNA stage that it decides on if it is going to be IgD or IgM
what does neutralize a virus mean
bind the virus in a spot so they can no longer infect the cells
what are biggest neutralizing antibodies
IgG IgM
what is main antibody for opsonization
IgG
what antibody for sensitization of mast cells
IgE
isotype
w/in a species. so humans all have IgG, IgM, etc. based on constant region
allotype
think allele. different alleles w/in a species. might get a different IgG from mom than you got from dad. might have slight differences in constant region
idiotype
porition that binds the antigen. b/w infections the antigen binding site will be different. the binding region that is different
CD3 present on
t cells
poly Ig is associated with
IgA
immunoglobulin superfamily
a lot of parts of the immune system that are related to each other, they have related genes, the domains are not only immunoglobulins
each variable region has how many hypervariable regions
3
hypervariable regions are also called
complementarity determining regions (CDR)
what does CDR stand for
complementary determining region
antigen binding site is composed of how many CDRs
3 light chain CDR
3 heavy chain CDR
