constant region

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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 ?
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.
Anne Dobree, Interim Director of Cambridge Enterprise, said, "We are pleased to have negotiated this license with Xencor, the most innovative company in the rapidly developing field of the engineering of antibody constant regions.
The newly patented method is an extension of that work, and also incorporates new computational methods, new understandings of molecular immunology, and data on the genetically constant regions from a growing number of genomic sequences of the mutating coronavirus.
Combining such superior variable regions with constant regions enhanced by the validated POTELLIGENT Technology supports our strategy of creating highly differentiated, competitive antibody products.
For example, the patent claims cover disrupted expression of mouse antibody constant regions as well as covering targeted deletion of mouse J segments.
HUMIRA was created using phage display technology, resulting in an antibody with human-derived heavy and light chain variable regions and human IgG1:K constant regions.
HUMIRA was created using phage display technology, resulting in an antibody with human-derived heavy and light chains variable regions and human IgG1:K constant regions.

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