Somatic DNA rearrangement generates functional rat immunoglobulin kappa chain genes: the J kappa gene cluster is longer in rat than in mouse |
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Authors: | A V Breiner C R Brandt C Milcarek R W Sweet E Ziv Y Burstein I Schechter |
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Institution: | 1. Department of Chemical Immunology, The Weizmann Institute of Science, Rehovot 76100 Israel;1. Department of Chemical Immunology, Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100 Israel;2. Department of Microbiology, Columbia University, New York, NY 10032 U.S.A.;3. Cancer Center, Institute for Cancer Research, Columbia University, New York, NY 10032 U.S.A. |
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Abstract: | The kappa immunoglobulin (Ig) genes from rat kidney and from rat myeloma cells were cloned and analyzed. In kidney DNA one C kappa species is observed by Southern blotting and cloning in phage vectors; this gene most likely represents the embryonic configuration. In the IR52 myeloma DNA two C kappa species are observed: one in the same configuration seen in kidney and one which has undergone a rearrangement. This somatic rearrangement has brought the expressed V region to within 2.7 kb 5' of the C kappa coding region; the rearrangement site is within the J kappa cluster which we have mapped. The rat somatic Ig rearrangement, therefore, closely resembles that seen in mouse Ig genes. In the rat embryonic fragment two J kappa segments were mapped at 2 and 4.3 kb 5' from the C kappa coding region. Therefore, the rat J kappa cluster extends over about 2.3 kb, a region much longer than the 1.4 kb of the mouse and human J kappa clusters. In the region between C kappa and the expressed J kappa of IR52 myeloma DNA, and XbaI site present in the embryonic kappa gene has been lost. A somatic mutation has therefore occurred in the intervening sequence DNA approx. 0.7 kb 3' from the V/J recombination site. Southern blots of rat kidney DNA hybridized with different rat V kappa probes showed non-overlapping sets of bands which correspond to different subgroups, each composed of 8-10 closely related V kappa genes. |
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Keywords: | Recombinant DNA Charon vector Ig gene evolution somatic mutation vk subgroups gene cloning bp base pair(s) C constant Ig immunoglobulin J joining kb kilobase pairs L-chain light chain V variable |
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