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Evidence for Control of Synthesis of the Variable Regions of the Heavy Chains of Immunoglobulins G and M by the Same Gene*
Abstract
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 NH2-terminal end of the γ- and μ-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.
Footnotes
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↵ † Recipient of an American Cancer Society postdoctoral fellowship. Requests for reprints should be sent to Dr. Wang, Department of Medicine, University of California Medical Center, San Francisco, California 94122.
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↵ ‡ Recipient of a special postdoctoral fellowship of the National Institutes of Health.
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↵ § Recipient of a postdoctoral fellowship of the National Institutes of Health.
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↵ * Supported by grants from the National Institutes of Health (AI-06281 and AI-09145); National Science Foundation (GB-5424); the Cancer Research Coordinating Committee of the University of California; the Jane Coffin Childs Foundation; and the American Cancer Society.
