In mammals Immunoglobulin heavy chain

1 in mammals

1.1 classes
1.2 regions
1.3 cows

in mammals
classes

there 5 types of mammalian immunoglobulin heavy chain: γ, δ, α, μ , ε. define classes of immunoglobulins: igg, igd, iga, igm , ige, respectively.

heavy chains α , γ have approximately 450 amino acids.
heavy chains μ , ε have approximately 550 amino acids.

regions

each heavy chain has 2 regions:

a constant region (which same immunoglobulins of same class differs between classes).

heavy chains γ, α , δ have constant region composed of 3 tandem (in line next each other) immunoglobulin domains have hinge region added flexibility.
heavy chains μ , ε have constant region composed of 4 domains.


a variable region differs between different b cells, same immunoglobulins produced same b cell or b cell clone. variable domain of heavy chain composed of single immunoglobulin domain. these domains 110 amino acids long.

cows

cows, bos taurus, show variation on general mammalian theme in heavy chain cdr h3 region has adapted produce divergent repertoire of antibodies present stalk , knob antigen interaction surface instead of more familiar bivalent tip surface. bovine cdr unusually long , contains unique sequence attributes support production of paired cysteine residues during somatic hypermutation. thus, in humans somatic hypermutation step targets v(d)j recombination process, target in cows on creation of diverse disulfide bonds , generation of unique sets of loops interact antigen. speculated evolutionary driver variation presence of vastly more diverse microbial environment in digestive system of cow consequence of being ruminants.