Influence of the Isotype of the Light Chain on the Properties of IgG1 (original) (raw)
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The Journal of Immunology, 2000
The association of HLA class I heavy chains with  2 -microglobulin ( 2 m) changes their antigenic profile. As a result, Abs react with either  2 m-free or  2 m-associated HLA class I heavy chains. An exception to this rule is the mAb TP25.99, which reacts with both  2 m-associated and  2 m-free HLA class I heavy chains. The reactivity with  2 m-associated HLA class I heavy chains is mediated by a conformational determinant expressed on all HLA-A, -B, and -C Ags. This determinant has been mapped to amino acid residues 194 -198 in the ␣3 domain. The reactivity with  2 m-free HLA class I heavy chains is mediated by a linear determinant expressed on all HLA-B Ags except the HLA-B73 allospecificity and on <50% of HLA-A allospecificities. The latter determinant has been mapped to amino acid residues 239 -242, 245, and 246 in the ␣3 domain. The conformational and the linear determinants share several structural features, but have no homology in their amino acid sequence. mAb TP25.99 represents the first example of a mAb recognizing two distinct and spatially distant determinants on a protein. The structural homology of a linear and a conformational determinant on an antigenic entity provides a molecular mechanism for the sharing of specificity by B and TCRs. The Journal of Immunology, 2000, 165: 3275-3283.
Structural Studies of Immunoglobulin G, M and a Heavy Chains
Annals of the New York Academy of Sciences, 1971
Examination of the intra-and interchain disulfide bonds of the yG globulins of a number of species have been quite revealing in showing relatively great variations in the number and position of the interchain bonds while demonstrating some greater degree of constancy in the intrachain bonds. This is particularly striking in the four subclasses of human y G which have been most carefully investigated to date.l This paper will review briefly some of the previously reported findings obtained with human yG and will present similar studies of the yM and yA globulin fractions.
Variable Regions of Heavy and Light Polypeptide Chains of the Same gamma G-immunoglobulin Molecule
Pnas, 1968
Each yG-immunoglobulin molecule contains two identical light chains and two identical heavy chains.' Light chains (designated x or X) consist of an amino terminal portion of variable amino acid sequence followed by a region of approximately the same length having a constant sequence. The variable regions of x chains fall into three subgroups based on the degree of homology of their amino acid sequences.2 It is currently believed that the diversity of sequence in antibody molecules is related to the variety of antigenic determinants to which they can bind. Heavy and light chains both appear to contribute to the antigenbinding site,' and thus heavy chains should also contain a variable region. The location, extent, and type of variability in heavy chains is being actively investigated in a number of laboratories.3-8
Proceedings of the National Academy of Sciences, 1975
Beta-Microglobulin, a low-molecular-weight protein structurally related to the homology regions of immunoglobulins, has been used to study the role of the intrachain disulfide bond in the unfolding of immunoglobulin domains. The intact protein could be reversibly unfolded in guanidine hydrochloride, as judged by circular dichroism and optical rotation. Similarly, reoxidation of the reduced protein, during transfer from high concentrations of guanidine to neutral aqueous buffer, yielded a product with spectral characteristics typical of the native protein. However, if the free SH groups were prevented from reoxidizing either by chemical modification or by holding them in the reduced state, the molecule appeared to be in the randomly coiled state even under conditions where the intact protein is in the native conformation, judged on the basis of chiroptical measurements. The complement-fixing activity exhibited by native beta-2-microglobulin was retained by the reduced and alkylated d...
Structural studies of human immunoglobulins
Archives of Biochemistry and Biophysics, 1965
Dissection of the G immunoglobulin molecules in man, using enzymic (1, 2) as well as chemical techniques (3, 4), has proceeded more rapidly than similar studies of the other two classes of Ig's and has provided a great deal of insight into the nature of the structural units and their genetic control. Using starch gel electrophoresis (3, 5) immunologic techniques (6, 7), and peptide analyses (8), it has been possible to demonstrate differences in light chains of different myeloma proteins, Bence Jones proteins, and antibodies. Similar techniques have also demonstrated differences in electrophoretic mobilities of the heavy chains of different myeloma proteins (5, 9), Except for a report showing that differences in the mobilifies of myeloma proteins correlate with the properties of the Fd fragments , little is known about the exact nature of these variations or their possible significance. A precise delineation of these differences has been hampered by difficulties in obtaining the Fd fragment (A piece), free of light chains or the Fc (fast) fragment.
Conformation of human IgG subclasses in solution
European Journal …, 1985
The structure of six human myeloma proteins: IgGl(Bal), IgG2(Klu), IgG3(Bak), IgG3(Het), IgG4(Kov) and IgG4(Pol), was studied in solution using small-angle X-ray scattering and hydrodynamic methods. For IgGl (Bal) and IgG3(Het) the experimental data, including radius of gyration (R",), radii of gyration of the cross-section (Rql, RqJ, intrinsic viscosity [q], sedimentation coefficient SO^^,^) and molecular mass, were interpreted in terms of structural models based on the Fab and Fc conformations, observed in crystal, by varying the relative positions of the Fab and Fc parts, i.e. their relative angles and distances.