Evidence for control of synthesis of the varible regions of the heavy chains of immunoglobulins G and M by the same gene.
Previous work indicated that the light chains of a monotypic immunoglobulins G2-K and M-K from a single patient (Ti1) are identical. Our present data show that the monotypic immunoglobulins G and M share idiotypic determinants not present in their isolated light chains or in any of a large number of other immunoglobulins tested, and that amino acid sequences of the first 27 residues from the NH(2)-terminal end of the gamma- and mu-chains are identical. These results support the hypothesis that at least two genes control the synthesis of each heavy and light chain and suggest that the monotypic immunoglobulin G and monotypic immunoglobulin M of this patient share three of the four genes involved. It is proposed that, during normal immunoglobulin synthesis, different cells of a single clone synthesize immunoglobulins M and G, and that the light chains and the variable segments of the heavy chains of the proteins of the two classes are identical within the clone. A genetic switching mechanism is suggested.
D000595:Amino Acid Sequence; D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D005809:Genes, Regulator; D006801:Humans; D007106:Immune Sera / Q000302:isolation & purification; D005779:Immunodiffusion; D007074:Immunoglobulin G / Q000032:analysis* / Q000302:isolation & purification; D007075:Immunoglobulin M / Q000032:analysis* / Q000302:isolation & purification; D007456:Iodine Isotopes; D008967:Molecular Biology; D009101:Multiple Myeloma / Q000276:immunology; D011817:Rabbits
D007106:Immune Sera; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007456:Iodine Isotopes