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An amino acid substitution determining G3m(g)
Journal of Biochemistry
|June 1, 1986
Abstract:
An allotypic G3m(g) marker-specific substitution was studied by sequence analysis of glycopeptides derived from myeloma proteins Ba (G3m(g+)) and Bu (G3m(g-)). The experimental results indicate that glutamic acid at position 295 is responsible for the specificity. Based on the results of chemical modification (Arg, Tyr, and Glu), this antigenic epitope is presumed to involve five sequential residues from Arg-292 to Tyr-296.
Insights
The G3m(g) marker specificity in human IgG subclasses is determined by glutamic acid at position 295. This finding aids in understanding IgG allotypic variations and their structural basis.
Area of Science:
- Immunogenetics
- Protein Chemistry
- Molecular Immunology
Background:
- Immunoglobulin G (IgG) subclasses possess allotypic markers that are genetically determined.
- The G3m(g) allotypic marker is a significant specificity within the IgG subclass.
- Understanding the molecular basis of allotypic markers is crucial for immunogenetic studies.
Purpose of the Study:
- To identify the specific amino acid substitution responsible for the G3m(g) allotypic marker.
- To elucidate the sequence of amino acid residues forming the antigenic epitope for G3m(g).
Main Methods:
- Sequence analysis of glycopeptides from myeloma proteins Ba (G3m(g+)) and Bu (G3m(g-)).
- Chemical modification of specific amino acid residues (Arginine, Tyrosine, Glutamic acid).
Main Results:
- A substitution at position 295, identified as Glutamic acid, is responsible for the G3m(g) specificity.
- Chemical modification studies suggest the antigenic epitope involves residues from Arginine-292 to Tyrosine-296.
Conclusions:
- Glutamic acid at position 295 is the key determinant for the G3m(g) allotypic specificity.
- The G3m(g) antigenic epitope is a sequential structure involving at least five amino acid residues.