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45 Cards in this Set
- Front
- Back
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where does an antigen bind on a antibody
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variable region
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where is the antibodies biological activity
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FC region
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what is the hinge in antibodies due to
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abundant proline (the hinge exposes the antibody to proteolytic degradation)
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how man AA is the variable and constant region of Heavy change
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variable 110 AA
constant 330 AA |
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what happens when antibody reacts with Papain
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cleaves Ig above the interdisulfide bond
2 Fab and 1 Fc Fab can still bind to antigen since their antigen binding site is still functional 1 Fc which can still bind to Fc receptor and start the complement |
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what happes when antibody reacts with Pepsin
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Ig is cleaved bellow the interdisulfide bond
1 F(ab)2 which still has parent antibody functions and is small and can enter cells/tissue |
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all heavy chains have 1 variable and 3 constant regions except for
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IgM and IgE they have more than 3 constant regions
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why is there variability in antigens
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so that one gene is not synthesized for every antigen
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what are Hypervariable regions
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complementarity determining regions
these are 3 areas within the variable region of heavy and light chain and give the antibody the majority of its variability |
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what are regions other than hypervariable region
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framework region
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what fascilitates the joining of the variable region and constant region
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Joining gene (j region). V REGION ALWAYS COMBINES TO THE J REGION NEVER DIRECTLY COMBINES TO THE C REGION
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what is a pseudogene
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a gene that is nonfunctional because it lacks protein coding
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what is the main difference with heavy and light chains
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heavy chains contain the D gene (diversity determining gene)
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what is a nascent polypeptide
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it still has the leader sequence attached
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what does VDJ recombinase do
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enables recombination between different gene segments that code variable and constant regions of light and heavy chains
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what is VDJ recombinase encoded by
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RAG1 and RAG2
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what happens if VDJ recombinase is not functional
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can lead to under/over secretion of an antibody or secretion of the wrong antibodies
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why are 2/3 of antibodies made non productive
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due to unwanted additions/deletions of nucleotides at either flanking sequence.
this is good because it increases diversity |
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what are isotypes
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classes of antibodies that arise due to variations in the constant regions of their HEAVY CHAINS
IgA IgG IgE IgM IgD |
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how many subclasses does IgG and IgA have
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IgG has 4 subclasses
IgA has 2 subclasses |
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what are allotypes
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differences in constant region of heavy and light chain w/in the same isotype (same class but different strains)
polymorphism may occur |
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what are idiotypes
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variation in the variable region specifically the CDR of the same isotype (same type of antibody but against different antigen)
as a result of idiotypes the capacity for the same antibody to bind another antigen increases |
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what does CDR determine
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antigen binding capacity of an antibody
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what are B-pleated sheets
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they give the antibody flexibility so it can bind different antigens
CONTAINS CDR/HYPERVARIABLE REGIONS |
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what does the variable domain do
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it binds antigens
contains the hypervariable region |
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what are the biological functions of the constant domain
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binds to Fc receptors
activation of complement system |
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what happens in the activation of the complement system
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B CELL GETS ACTIVATED BY AN ANTIGEN
DIFFRENTIATION/PROLIFERATION OF NAIVE B CELL B CELL BECOMES AN EFFECTOR CELL EFFECTOR CELL STARTS TO SECRETE ANTIBODIES THAT RECOGNIZE THE SAME ANTIGEN THAT IT INITIALLY REACTED TO |
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WHAT ARE THE PROPERTIES OF IgG
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most abundant antibody
2ndary responder crosses the placenta (this is very important for fetus development) OPSONIZES secreted/present in breast milk ACTIVATES COMPLEMENT BUT NOT AS WELL AS IgM |
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what is the best compliment activator of IgG
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IgGIII
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what are the Fc receptors that IgG is recognized by
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FcGAMMAR1
FcGAMMAR3a FcGAMMAR3b FcGAMMARn |
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what does FcGAMMAR1 do
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plays important role in antibody dependent cell mediated cytotoxicity (ADCC)
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what does FcGAMMAR3a do
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binds to ADCC via NK cells
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what does FcGAMMAR3b do
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responsible for production of superoxides by neutrophils
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what does FcGAMMARn do
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mediates transplacental passage
this is how maternal IgG gets to the fetus |
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what are the properties of IgA
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present in mucosal surfaces/secretions(saliva tears sweat)
secreted by plasma cells at basal surface of epithelia MADE AS A DIMER LINKED BY J CHAIN (NOT J GENE) transported across epithelium (important for mucosal immunity) |
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how is IgA transported across the epithelium
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via Poly Ig receptor (FcALPHA-R) which recognizes it
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what are the fucntions of IgA
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block pathogen adherence giving it mucosal immunity
binding to FcALPHA-R |
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what are the properties of IgM
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best complement activator
1st serum immunoglobulin in primary response when IgM is fully secreted forms PENTAMER good agglutinator due to many antigen binding sites when in soluble form it is the best activator of complement b/c has many antigen binding sites |
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what is the monomer of Igm
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membrane IgM on B cell surface
-it binds to B cell antigen receptor (BCR) |
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what are the properties of IgM pentamer
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low affinity (in single bonds) but high avidity (due to multiple bond interactions)
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what does it mean when you say IgM and IgD can be coexpressed
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this is due to both of them being on the B cell surface
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what are the properties of IgD
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on B cell surface
short Hl because is has as large Hinge region unknown function MADE IN VERY SMALL AMOUNTS |
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what are the properties of IgE
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ALLERGY
LEAST ABUNDANT ISOTYPE BUT CAPABLE OF TRIGGERING MOST POWERFUL IMMUNE RESPONSES bound to FCER1 on mast cell sruface antigen/allergen binding to IgE causes degranulation of mast cell external surface protection |
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what is the physiological role of IgE
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initiate acute inflammation
protect from parasites |
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what is an Epitope
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structural feature of an antigen that binds to antibody or T cell receptor
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