Document Detail

Conformational dependency of human IgG heavy chain-associated Gm allotypes.
MedLine Citation:
PMID:  8455636     Owner:  NLM     Status:  MEDLINE    
Human IgG allotypic markers Gm(a)[Glm(1)], Gm(x)[Glm(2)]; Gm(f)[Glm(4)], Gm(b)[G3m(5) and (11)] and Gm(g)[G3m(21)] were studied after chemical modification of IgG histidines by diethylpyrocarbonate, tyrosines by N-acetylimidazole and lysines by formaldehyde and sodium borohydride. Degrees of substitution were estimated by trinitrobenzenesulfonic acid assay. IgG of known Gm phenotype isolated from serum of hyperimmune anti-tetanus toxoid donors was studied. Histidyl modification resulted in virtually complete loss of Gm(a) and Gm(g) antigenicity but preservation of Gm(x), Gm(b) and Gm(f). Reconstitution of the histidyl residues using hydroxylamine resulted in virtually complete restoration of Gm(a) and Gm(g) antigenicity. Histidine modification resulted in no significant decrease in ELISA anti-tetanus antibody activity. Alteration of tyrosyl residues using N-acetylimidazole considerably diminished Gm(a) and Gm(f) expression. This effect was reversed by hydroxylamine treatment. Moreover, chemical alteration of tyrosyl residues produced a complete loss of Gm(g) antigenicity which was only partially restored after deacylation. A urinary H chain fragment containing the VH region directly linked to C gamma 3 which contained the Gm(a) specific and Gm(x) specific amino acid residues was positive for Gm(a) but negative for Gm(x). Another urinary H chain fragment containing only the C gamma 3 domain was negative for both Gm(a) and (x). These findings indicate that Gm allotypic markers may depend on conformational determinants in which strongest expression for Gm(a) and (x) depends on structures expressed by C gamma 3 linked to C gamma 2 domains. Although RFs react with the region encompassing the C gamma 2-C gamma 3 interface, Gm-specificities of such reactions are affected allosterically through single or double amino acid substitutions at a relatively distant site.
R C Williams; C C Malone; A Solomon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Molecular immunology     Volume:  30     ISSN:  0161-5890     ISO Abbreviation:  Mol. Immunol.     Publication Date:  1993 Mar 
Date Detail:
Created Date:  1993-04-22     Completed Date:  1993-04-22     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7905289     Medline TA:  Mol Immunol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  341-51     Citation Subset:  IM    
Department of Medicine, University of Florida, Gainesville.
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MeSH Terms
Amino Acid Sequence
Antibody Specificity* / drug effects,  physiology
Bence Jones Protein / chemistry,  immunology
Histidine / chemistry,  pharmacology
Immunoglobulin G / chemistry,  immunology*
Immunoglobulin Gm Allotypes / immunology*
Immunoglobulin Heavy Chains / chemistry,  immunology*
Lysine / chemistry
Molecular Sequence Data
Protein Structure, Tertiary*
Rheumatoid Factor / immunology
Sulfhydryl Reagents
Tetanus Toxoid
Tyrosine / chemistry
Grant Support
Reg. No./Substance:
0/Borohydrides; 0/Imidazoles; 0/Immunoglobulin G; 0/Immunoglobulin Gm Allotypes; 0/Immunoglobulin Heavy Chains; 0/Sulfhydryl Reagents; 0/Tetanus Toxoid; 16940-66-2/sodium borohydride; 2466-76-4/N-acetylimidazole; 55520-40-6/Tyrosine; 56-87-1/Lysine; 71-00-1/Histidine; 9006-99-9/Bence Jones Protein; 9009-79-4/Rheumatoid Factor

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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