Medical Microbiology

Immunoglobulinscontainnumerousdomains,asillustratedbythestruc-
tureofIgG.InmonomericIgGeachdomainconsistsofaproteinsegment
whichisapproximately 110 aminoacidsinlength.Bothlightchainspossess
twosuchdomains,andeachheavychainpossessesfourorfivedomains.The
domainstructurewasfirstrevealedbycomparisonoftheaminoacidse-
quencederivedfrommanydifferentimmunoglobulinsbelongingtothe

TheB-CellSystem 51

BasicImmunoglobulinStructures

Fab Fab

Fc

Papain

L chain

L chain

H chain

H chain

Fv

S piece

J chain

αλ oder κ

J chain

λ or κ μ

IgA

IgM

IgG IgE

γ

λ or κ

ε

Pepsin

Splitting of

disulfide bonds

F(ab') 2

Ig monomer ABS

Variable

domains

Constant

a domains

b

2

Kayser, Medical Microbiology © 2005 Thieme