Organization of immunoglobulin genes.

The nucleotide-sequence determination of a cloned, embryonic Vlambda gene directly demonstrated that V genes are separate from a corresponding C gene in embryonic cells. Analysis by restriction enzymes of total cellular DNA from various sources strongly suggested that the two separate immunoglobulin genes become continuous during differentiation of B lymphocytes. There seems to be a strict correlation between the joining event and activation of the joined genes. Cloning of more immunoglobulin genes from embryo and plasma cells will not only provide direct demonstration of such a gene-joining event but also help in the elucidation of a possible relationship of the event to gene activation mechanisms.