constant region

Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Related to constant region: hinge region

im·mu·no·glob·u·lin (Ig),

One of a class of structurally related proteins, each consisting of two pairs of polypeptide chains, one pair of light (L) low molecular weight chains (κ or λ), and one pair of heavy (H) chains (γ, α, μ, δ, and ε), usually all four linked by disulfide bonds. On the basis of the structural and antigenic properties of the H chains, immunoglobulins are classified (in order of relative amounts present in normal human serum) as IgG (7S in size, 80%), IgA (10-15%), IgM (19S, a pentamer of the basic unit, 5-10%), IgD (less than 0.1%), and IgE (less than 0.01%). All of these classes are homogeneous and susceptible to amino acid sequence analysis. Each class of H chain can associate with either κ or λ L chains. Subclasses of immunoglobulin, based on differences in the H chains, are referred to as IgG1, etc.
When split by papain, IgG yields three pieces: the Fc piece, consisting of the C-terminal portion of the H chains, with no antibody activity but capable of fixing complement, and crystallizable; and two identical Fab pieces, carrying the antigen-binding sites and each consisting of an L chain bound to the remainder of an H chain.
Antibodies are immunoglobulins, and all immunoglobulins probably function as antibodies. However, immunoglobulin refers not only to the usual antibodies, but also to a great number of pathologic proteins classified as myeloma proteins, which appear in multiple myeloma along with Bence Jones proteins, myeloma globulins, and immunoglobulin fragments.
From the amino acid sequences of Bence Jones proteins, it is known that all L chains are divided into a region of variable sequence (VL) and one of constant sequence (CL), each comprising about half the length of the L chain. The constant regions of all human L chains of the same type (κ or λ) are identical except for a single amino acid substitution, under genetic controls. H chains are similarly divided, although the VH region, although similar in length to the VL region, is only one third or one fourth the length of the CH region. Binding sites are a combination of VL and VH protein regions. The large number of possible combinations of L and H chains make up the "libraries" of antibodies of each individual.

constant region

The portion of an immunoglobulin's heavy and light chains having an amino acid sequence that does not vary within a given class or subclass of immunoglobulin.

constant region

the part of an immunoglobulin in which the amino acid sequence is relatively constant in all molecules of that class of immunoglobulin. Compare variable region.

constant (C) region

an area of an IMMUNOGLOBULIN molecule that shows little chemical and structural variation between molecules with different specificities. Compare VARIABLE REGION.
References in periodicals archive ?
0, the frequency point where the dispersion curves change direction and the complex waves appear moves from the attenuation constant region as seen in Figure 4 into the phase constant region as seen in Figure 3.
After sorting them in ascending order, we identify constant regions and interval regions between two constant regions as Eq.
The antigen for the murine scFv that was used in some constructs with human constant regions was hen egg lysozyme (Gal d4) (Sigma).
The human immunoglobulin constant regions were synthesized from cDNA derived from human peripheral blood mononuclear cells employing standard reaction conditions.
The genes for human IgG1 and IgG4 heavy chain constant regions (IGHG1 and IGHG44) were amplified using PCR primers containing an AscI and a KpnI site ([[gamma]1: GAT CGG TAC CGA TCG GCG CGC CCA AAT CTT GTG ACA AAA CT CAC, [gamma]4: GAT CGG CGC GCC TTC CAC CAA GGG CCC ATC CGT CTT CCC CCT) and a SfiI site ([gamma]1: GAT CGG CCC AGC CGG CCT CAT TTA CCC GGA GAC AGG GAG AGG CTC TTC, [gamma]4: GAT CGG CCC AGC CGG CCT CAT TTA CCC AGA GAC AGG GA), the [gamma]1 [C.
For amplification of the genes for the human IgE heavy chain constant regions (IGHE) we used primers containing an AscI site (GAT CGG CGC GCC CAT CCG TCT TCC CCT TGA), an SfiI site, a 4xhis-tag (GAT CGG CCC AGC CGG CCT CAT TTA CCG GGA TTT ACA GAC AC), and for the s [C.
Subsequently, the DNA was ligated into the vectors containing the signal sequence and the particular constant regions.
After assembly of the leader sequences and the constant regions, the variable regions were then introduced via the SgfI and the SbJI sites, or the AscI and SwaI sites, respectively.

Full browser ?