Flashcards in Immunoglobulin structure and fucntion Deck (53)
what are antibodies also termed as?
where are immunoglobulins present in?
Plasma, tissues, secretions and lymphatics
what is immunoglobulins a product of?
humoral immune system
what are immunoglobulins secreted by?
activated B cells
What are the five classes of immunoglobulin?
what do these 5 classes of immunoglobulins do?
Provide recognition function and trigger effector functions
Describe the structure of an antibody molecule.
Consists of two heavy chains and two light chains. The hinge that connects the two heavy chains is disulphide bonds and non covalent interactions also hold chains together
what do both the heavy and Light chains have?
what does the Fab region stand for?
fragment antigen binding
what does the Fc region stand for?
Relate Fab and Fc regions to the dual function of antibodies.
-Recognition function- Binding to antigen via Fab arms
-Effector function- Clearance mechanisms via interaction of Fc with effector molecules
what are the two types of light chains?
Do light chains in antibodies classes differ?
No -All antibody classes use these same light chains
what do the light chains fold up into?
2 globular domains termed VL and CL
What determines the class of antibody?
the heavy chains
Name the different heavy chains in the 5 classes.
IgG gamma heavy chain
IgA alpha heavy chain
IgM micro heavy chain
IgE. epsilon heavy chain
IgD delta heavy chain
what does the heavy chains fold up into?
-IgG , IgA, IgD into 4 globular domains and for IgM and IgE 5 globular domains
what is needed for antibody molecules to complete their effector function?
sugar attachments - oligosaccharides
With millions of different antigens, what do antibodies do (adapter molecules)?
produce small number of effector molecules
what was revealed when comparing sequences of different antibodies?
There were three hypervariable loops or CDRs (complementarity determining region) in each V domain
what do hyper variable loops or CDRs form?
antigen binding site
What happens when Vh (variable heavy domain) and Vl (variable light domain) are paired?
their 6 CDRs create the antigen-binding site
what makes up the antigen binding site?
6 Hypervariable regions or complementarity determining regions (CDR) - 3 in VH and 3 in VL
how does the antigen binding site and antigen bind?
Complementarity of 3D structures
What is the most abundant Ig in plasma?
Describe the shape of the IgG?
2 HC of 50 kDa, 2 LC of 25 kDa
What are the subclasses of IgG?
4 subclasses - IgG1, IgG2, IgG3, IgG4
what is IgG efficient at triggering?
complement and phagocytosis via Fc receptors
what characteristic does IgG have that no other Ig's have?
Only Ig class to cross placenta from mother to foetus - protects baby in first months of life