Untitled - D Ank Unlimited

immunoglobulin M (IgM) 373 immunoglobulin M (IgM)
Anode
+
5'
V H
5'UT
L V
IVS
Albumin
D
Alpha-1-globulin
V D J en C µ C δ
S
codon 1
Cγ1 hCγ2 Cγ3 Alpha-2-globulin
C γ 3
3'
acaaaaacc
cacagtg
C γ 1
C α 1
C γ 2
C γ 4
C α 1 C α 2 C α 3
S S S S S S S
Beta globulin
Gamma globulin
(Immunoglobulins)
ψ ε 1
ψ γ
Immunoglobulin genes.
Cathode
Electrophoresis of serum protein showing the gammaglobulin region that
contains the immunoglobulins.
L 1 V 1 L 2 V 2 L n V n
L
V
D
J
C
E
J H
C µ Cδ Cγ3 Cγ1 bCγ2b Cγ2a Cε Cα 5' 3 2 1
3'
L 1 V 1 L n V n
= Promoter
= Leader sequence
= Variable regions
= Diversity regions
= Junction regions
= Constant region coding block
= Enhancer sequence
Mouse immunoglobulin gene.
–
D 1
D n
C α 2
is a pentameric molecule with five four-chain monomers
joined by disulfide bonds and a J chain, with a total molecular
weight of 900 kDa. Theoretically, this immunoglobulin
has ten antigen-binding sites. IgM is the most efficient
immunoglobulin in fixing complement. A single IgM
pentamer can activate the classic pathway. Monomeric IgM
is found with IgD on B lymphocyte cell surfaces, where it
serves as a receptor for antigen. It is the first immnoglobulin
expressed on the B cell surface and the first antibody
secreted in an immune response. Because IgM is relatively
large, it is confined to intravascular locations. IgM is
particularly important for immunity against polysaccharide
antigens on the exterior of pathogenic microorganisms. It
J
D n
Immunoglobulin gene rearrangement.
= Switch sequence
E
J
C µ
E
C µ
C ε
Germ line DNA
configuration
Rearrangement
B cell DNA
I