Heavy chain-producing variants of a mouse myeloma cell line.

Eleven variants producing only heavy (H) chains have been isolated from the P3 cell line after mutagenesis with either ICR-191 or nitrosoguanidine. The H chains produced by these variants are similar both in molecular weight and by peptide maps with the parental H chain. H chains dimerize intreacellularly, are not secreted but persist as stable cytoplasmic proteins. No evidence for the continued synthesis of light (L) chains of L chain fragments has been found in these variants. These studies show that, in the P3 cell line, the synthesis of H chains can continue in the absence of detectable L chain synthesis.