Coexpression of micro and gamma-1 heavy chains can occur by a discontinuous transcription mechanism from the same unrearranged chromosome

The BCL(sub 1) leukemia B-cell line produces immunoglobulin M and G heavy chains which do not undergo constant region gene rearrangement and have identical variable regions. Further characterization of these immunoglobulins showed that their micro and gamma heavy chains are coexpressed by discontinuous transcription. This involves RNA trans-splicing ofthe micro pre-RNA initiated 5' of the variable-diversity-joining region to the gamma-1 pre-RNA initiated 5' of the gamma-1 constant region.