Immunoglobulin Structure and Function Flashcards
What are Immunoglobulins?
Antibodies also termed immunoglobulins
Present in plasma, tissues, secretions and lymphatics
Product of humoral immune system
Secreted by activated B cells - plasma cells
What are the 5 classes of immunoglobins and what do they do?
Immunoglobulin G (IgG)
IgM
IgA
IgD
IgE
Provide RECOGNITION function and
trigger EFFECTOR functions
What is the immunoglobulins structure?
What os the Dual function of antibodies?
Recognition function
Binding to antigen - Fab arms
Effector function
Clearance mechanisms - interaction of Fc with effector molecules
What is the V domain?
VH is the heavy chain in the inside of the immunoglobulin.
VL is the light chain on the outside of the immunoglobulin.
What does CDR stand for?
CDR = complementarity determining region
What forms the antigen binding sites?
Hypervariable loops or CDRs form the antigen binding site
CDRs form close-lying loops at one end of V domain
When VH and VL domains are paired their 6 CDRs create the antigen-binding site
How mayn Hypervariable regions or complementry determining regions (CDR) are there in VH and VL
•6 Hypervariable regions or complementarity determining regions (CDR) - 3 in VH and 3 in VL
What are the 4 different types of Allotropes of carbon?
Diamond
Graphite
Lonsdaleite
Buckminsterfullerene - C60
Give the facts about IgG.
- Most abundant Ig in plasma
- Y shaped, 4 sub units
- Very efficient at triggering complement
and phagocytosis via Fc receptors
- Only Ig class to cross placenta from mother
to foetus - protects baby in first months of life
Give facts about IgM.
- Only in plasma and secretions
- too large to enter tissues - 5 Y-shaped units
Joined by J chain and disulphide bridges
Heavy chain has 5 globular domains
- Ten binding sites for antigen - very good at
agglutinating particles eg viruses
- Very efficient at activating complement
Give facts about IgA
- Important serum Ig (2-3 mg/ml)
- Major antibody in seromucous secretions e.g. saliva, milk, colostrum gut
- Class of antibody first encountered by many invading bacteria and viruses
- Two subclasses - IgA1, IgA2
Give fact about IgD
Found on surface of lymphocytes
Give facts about IgE effector functions.
- Expressed on mast cells and basophils
- Associated with allergic response
What are the effector molecules?
- Fc receptors - receptors which bind specifically
to the Fc region of immunoglobulins
- Complement
