Immunoglobulin K chain genes in mouse hybridoma PTF-02 and parent myeloma. Insertion of hybridoma K gene into the plasmid pSV2-gpt.

The mouse myeloma line P3-X63-Ag8.653 currently used as the parent line for hybridoma construction contains only one (non-productive) gene for immunoglobulin K chains. The allelic gene is lost. In the mouse hybridoma PTF-02 two K genes can be found. One is identical with the gene of the myeloma parent line, the other originates in lymphocytes and is transcribed and translated in the K chain of the antibody secreted by the hybridoma. From the gene library of hybridoma PTF-02 in phage Charon 28 both K genes were isolated. Restriction endonuclease mapping and Southern blot hybridization demonstrated that the fragment comprising the lymphocyte gene was of the size (7.5 kb) sufficient to carry all exons, transcription and translation units. This gene was then recloned in the plasmid pBR322 and shuttle plasmid pSV2-gpt, which opens up possibilities for transfection of lymphoid cells and for study of the regulation of individual gene expression.