Antibody Synthesis

Front 1

How are antibodies made?

Back 1

Antibodies are secreted proteins made by B cells
-H and L chain mRNAs are translated into proteins by membrane-bound ribosomes.
-H and L chain polypetides are translocated into the ER as they are synthesized
-In ER, H and L chains are assembled into a complete antibody molecule (2H chains and 2 L chains joined by S-S bonds)

Front 2

After antibodies are completed, where do they go?

Back 2

They move from ER and through the Golgi
-Vesciles bud off from Golgi and move to plasma membrane where vesicles fuse with plasma membrane and antibodies are released into extracellular fluids

Front 3

Where are secreted antibodies most likely to be found?

Back 3

In the blood. Also found in mother's milk, tears, saliva, GI secretions and muscus

Front 4

What are the main types of secreted antibodies?

Back 4

IgM, IgA IgG

Front 5

People with allgeries make lots of which antibody

Back 5

IgE

Front 6

Why can antibodies of different isotypes can recognize the same antigen?

Back 6

Because they have the same V region but their C regions are different

Front 7

Describe Secreted IgM

Back 7

-Is a pentamer consisting of 5 IgM monomers that are joined to each other by S-S bonds
-Two of the IgM monomers are connected by a polypetide called a J chain (joining chain)
-Antigen binding sites of IgM antibodies have low binding affinity, but the pentamer IgM has high avidity (total binding strength)
-Because the more binding sites the greater the total binding strength
-It is the major class of serum immunoglobulin produced during a primary response (first time we encounter a certain antigen)
-Main role is to kill bacteria (complement proteins lyse bacteria coated with IgM)

Front 8

Describe Secreted IgG

Back 8

-Major class of serum immunoglobulin made during secondary responses (the second time you encounter a certain antigen)
-IgG kills bacteria in 2 ways
1) Complement proteins kill bacteria coated with IgG-amino acid sequence in the gamma chain constant region can bind complment proteins
2) Opsonization - phagocytes ingest bacteria coated with IgG antibodies more readily.

IgG antibodies from the mother can cross the placenta and provide protection for the fetus

Front 9

Describe IgA

Back 9

In serum, IgA is a monomer
-In bodily secretions (salvia) IgA is a dimer
-Two monomers are connected by J chain
-Dimeric Iga in bodily secretions is associated with polypetide called the secretory piece
-Secretory chain helps Iga cross layers of epithelial cells and to get to various body sites like the gut

Front 10

What is the main purpose of IGA

Back 10

IT is the main immunoglobulin class in bodily secretions (tears, salvia, mucus, mother's milk)
-Purpose is to bind and to neutralize pathogens
-Prevents the attachment of pathogens to host surfaces

Front 11

Describe secreted IgE

Back 11

-It is secreted into the serum but almost all of it binds to mast cells and basophils
-Only class of antibody that can bind to the eplison chain constant region
-It is the antibody responsible for triggering allergic reactions. When IgE on mast cell or basophil binds an antigen, the cell degranulates and releases large amounts of histamine and histamine causes allgeric responses

Front 12

what is the function of IgE

Back 12

main class of immunglobunlin induced in response to infection by parasites such as intestinal worms
-mast cell degranulation results in diaherra and vomitting which helps expel the worms