14. Antibody structure and function Flashcards Preview

Immunology > 14. Antibody structure and function > Flashcards

Flashcards in 14. Antibody structure and function Deck (18):

Antibody structure divide to

1, Fab
2. Fc


Antibody - Fab part structure and function

consistists of light (L ) and hravy (H) chains and recognizes antigens --> determines idiotype idiotypeQ unique antigen binding pocket
only 1 antigenic specificity expressed per B cell


Idiotype is the

distinctive sequene and region that makes any immunoglobulin / TCR unique from others of the same type which is its variable region


Antibody - hinge region

flexible amino acid stretch in the central part of the heavy chains of the IgG and IgA immunoglobulin classes, which links these 2 chains by disuldfide


Antibody - Fab part structure and function

complement binding
Carboxyl terminal
Carbohydrate side chains
Determines isotype (IgM, IgG etc)


Antibody L and H chains are binded by



Antibody - parts of heavy chain

From Fab to Fc
VH - CH1- Hinge ( Fab) CH2 - CH3 (Fc)


Antibody - parts of light chain

Froma Fab to FcQ


Generation of antibody diversity

Antigen independent
1. Random recombination of Vj (light) or V(D)J heavy genes
2. Random combination of heavy chains with light chains
3. Random addition of nucleotides to DNA during recombination by terminal deoxynucleotidyl transferase


Generation of antibody specificity

Antigen depended
1. Somatic hypermutation and affinity maturation ( variable region)
2. Isotype switching (constant region)


Antibody function according to area ( and definition)

1. opsonization ( CH2 and CH3) --> antibody promotes phagocytosis
2. Neutroalizarion (FAB) prevents bacterial adherence
3. COmplement activation (CH2) --> activates complement --> enhance lysis ( Membrane attack complex (MAC) and opsonization)


• The ____ (Fab/Fc) portion of immunoglobulins ____ and ____ fixes complement.

Fc; M; G


• What are the 4 Cs to remember about the Fc fragment of an antibody? What additional feature is important?

Constant region, Carboxy terminal, Complement binding, Carbohydrate side chains; it determines the isotype


• Name four mechanisms by which antibody diversity is generated.

Random V(D)J recombination; random heavy-/light-chain combinations; somatic hypermutation; terminal deoxynucleotidyl transferase nucleotides


• A researcher is studying the two bacteria-killing processes that are enhanced when an antibody activates complement. What are they?

Opsonization and lysis


The antigen-binding fragment of an antibody is the ____ (Fab/Fc) region; this region can be specific for how many antigens?

Fab; only one antigen, thus determining idiotype with its unique antigen-binding pocket


• A new drug enhances the three ways that antibodies promote activity against antigens. Name these three ways.

Opsonization (promotes phagocytosis), neutralization (prevents bacteria adhering), and complement activation


• Which chain contributes to the Fab and Fc regions of an antibody? Which chain contributes only to the Fab region?

Heavy chain; light chain