Immunoglobulines Flashcards
what other names do immunoglobulines receive?
gammaglobulines or antibodies
which cells produce immunoglobulines?
plasma cells
5 main classes of antibodies
IgG, IgA, IgM, IgE, IgD
what is a BCR?
B-Cell Receptor, membrane bound immunoglobulines
what is an antibody?
secreted immunoglobulines, proteins circulating in blood
name the parts of the basic structure of the antibody
- heavy chains
- light chains
- disulphide bonds
- Hinge region
- FC region
- short carbohydrate chains
what are disulphide bonds for?
they connect the H chain with the L chain
what is the function of the Hinge region?
2 disulphide bonds in the mid-region that give flexibility to the antibody
what is the FC region?
part of the andibody (the stem) which is recognized by the immune system cells
what are the short carbohydrate chains for?
(attached to each H chain) they are important for solubility for transportation in blood
molecular weight of L chains
25 kDa (kilodaltons)
amount of aminoacids of L chains
220 aminoacids
types of L chains
- lambda (encoded in chromosome 22 - 40%)
- kappa (enconded in chromosome 2 - 60%)
molecular weight of H chains
50-70 kDa (kilodaltons)
amount of aminoacids of H chains
440 aminoacids
where are all types of H chains encoded in?
chromosome 14
what is the variable region?
the fisrt 110 aminoacids of both L and H chains can be variable; this region interacts with the epitopes
what do Variable L chain + Variable H chain form?
antigen binding site
what is the name of the variable aminoacid sequences?
hypervariable regions or complimentarity determining regions (CDR)
what is the function of the CDRs?
they have direct contact with the epitope
what are the framework residues (FR)?
intervening sequences between the CDRs, they don’t interact with epitopes
what is the constant region?
region where aminoacids have little or no variability at all
IgG
- most common class
- 4 subtypes
- the only one capable of crossing the placenta (provides immunity to fetus)
- secreted into mother’s milk
IgA
- found in tears, saliva, respiratory and intestinal secretions, colostrum
- produced by B-cells located in mucous membranes
- most synthesized immunoglobuline
IgM
- most common present as the antigen receptor on B-cell surface
- 10 antigen binding sites (5 Y-shaped units)
- effective at attacking bacteria
- aglutinate together bacteria to be easier phagocyted
IgE
- low concentrations
- each H chain has an extra constant domain
- the extra CH4 allows binding to basophils and mast cells
- involved in allergic reactions
- protect agains parasite infections
IgD
- function as BCRs
- low concentrations in blood
- not clear function
