Untitled - D Ank Unlimited

immunoglobulin α chain 368 immunoglobulin deficiency with elevated IgM
Ig IgG IgM IgA
Serum concentration
(mg/dl)
have intestinal lymphangiectasia, arthritis, gluten-sensitive
enteropathy, allergies, and myotonic dystrophy. They may
also develop low molecular weight IgM antibodies against
food substances such as milk. Other clinical features may
include sinopulmonary infections, cirrhosis, and autoimmune
disease. IgA deficiency is detectable in approximately
three fourths of ataxia telangiectasia patients. Intravenous
immune globulin with only minute quantities of IgA may
be beneficial to these patients.
immunoglobulin chain
A 58-kDa, 470-amino-acid residue heavy polypeptide
chain that confers class specificity on immunoglobulin
A molecules. The chain is divisible into three constant
domains, designated C H1, C H2, and C H3, and one variable
domain, designated V H. A hinge region is situated
between C H1 and C H2 domains. An additional segment of
18 amino acid residues at the penultimate position of the
chain contains a cysteine residue where the J chain can be
linked through a disulfide bond. The IgA subclass is divisible
into IgA 1 and IgA 2 subclasses, reflecting two separate
α chain isotypes. The α-2 chain has two allotypes designated
A2m(1) and A2m(2) and does not have disulfide
bonds linking H to L chains. Subclass-specific residues
are found in a number of positions in C H1, the hinge
region, and C H2, where α-1 and α-2 chains differ but α-2
chains are the same. Differences in the two α chains are
found in two C H1 and five C H3 positions. Thus, humans
have three varieties of α heavy chains.
immunoglobulin class
The subdivision of immunoglobulin molecules based on
antigenic and structural differences in the Fc regions of
their heavy polypeptide chains. Immunoglobulin molecules
belonging to a particular class have at least one constant
region isotypic determinant in common. The different classes
such as IgG, IgM, and IgA designate separate isotypes.
Because the light chains of immunoglobulin molecules are
one of two types, the heavy chains determine immunoglobulin
class. There is about 30% amino acid sequence homology
among the five immunoglobulin heavy chain constant
regions in humans. Heavy chains (or isotypes) also differ in
carbohydrate content. Immunization of a nonhuman species
800–1700 50–190 140–420 0.3–0.4