constant region

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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.
Farlex Partner Medical Dictionary © Farlex 2012

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.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

constant (C) region

an area of an IMMUNOGLOBULIN molecule that shows little chemical and structural variation between molecules with different specificities. Compare VARIABLE REGION.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
The variable region of the aptamers are represented in red, the flanking constant regions of the aptamers are in black, and the nucleotide residues that varied between all clones "mutations" are represented in blue.
The uniform distributed load is applied on surface D of the constant rectangular cross section flexure hinge to keep the deflection of the rigid beams constant, and the deflection of the constant region can be expressed as
It appears as evanescent modes in the attenuation constant region and changes to forward waves at the frequency point, [OMEGA] = 0.
(5), dom([f.sub.i]) can be divided into two subsets, [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is constant regions and the same to [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], which is the set of [f.sub.i]'s comparative values of used in [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] are interval regions between two constant regions.
The construction of human-mouse chimeric antibody basically involves cloning and ligating of the variable region genes of mouse mAbs into expression vectors, which have heavy- and light-chain immunoglobulin constant regions. A simple methodology for this conversion will be described here in a step-by-step manner.
As a class of proteins, immunoglobulins lend themselves to multiplexing since they contain numerous proteotypic peptides including clone-specific variable regions, isotype-specific constant regions, and subclass-specific regions.
MAb Antigen Binding site P4-14G6 cTnI aa 1-15 23C6 cTnI aa 15-25 4C2 cTnI aa 23-29 M155 cTnI aa 26-35 10F4 cTnI aa 34-37 19C7 cTnI aa 41-49 247 cTnI aa 65-74 560 cTnI aa 83-93 8E10 cTnI aa 86-90 415 cTnI aa 104-119 84 cTnI aa 117-126 M46 cTnI aa 130-145 8I7 cTnI aa 137-148 581 cTnI aa 143-152 441 cTnI aa 148-158 625 cTnI aa 169-178 472 (a) cTnI aa 182-191 MF4 cTnI aa 190-196 p45-10 cTnI aa 195-209 7B9 TnC 3D3 Human IgG Constant region 2C11 Human IgG1 Constant region 3C7 Human IgG2 Hinge region 5G12 Human IgG3 Hinge region 5C7 Human IgG4 Constant region Binding sites or epitopes are also given if they were specified by the manufacturer.
Siltuximab is a chimeric immunoglobulin comprising the variable antigen-binding region of a mouse antibody and the constant region of human IgG1[kappa] (1).
The [gamma]1, [gamma]4, and s heavy chain constant regions and a corresponding light chain constant region were amplified from a cDNA library derived from human peripheral blood mononuclear cells (data not shown).
Localization of an Fc-binding reactivity to the constant region of human IgG4.
Chimeric antibodies are composed of murine variable regions fused onto human constant regions. Humanized antibodies are produced by grafting murine hypervariable regions on amino acid domains into human antibodies.
Compared to the time-consuming and laborious mutations in development of humanized mAb, chimeric mAb is prepared by recombining of whole murine variable regions, not only CDRs, with human constant regions. Furthermore, in contrast to the repeating administration of the mAb against tumor, the dosage of the anti-infective mAb is not so frequent.

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