Abstract
The amino acid sequences of the lambda chains of two mouse immunoglobulins have been determined. No variations were found between these proteins. The results are compatible with earlier fingerprinting analysis of the two chains, where no differences in the tryptic peptides could be demonstrated. The lack of sequence variations could be the result either of a peculiarly restricted expression of the lambda variable-region genome in the BALB/c myelomas or a small number of germ-line genes involved in the biosynthesis of light chains of the lambda type.