Amino acid sequence diversity in mouse lambda 2 variable regions.

The lambda-chains of immunoglobulins from BALB/c mice constitute the simplest system presently available for studying patterns of variable-region diversity. The limited number of V lambda and J lambda germ-line gene segments facilitates comparison of expressed and germ-line sequences. We report here the complete amino acid sequence of the variable regions of three lambda 2 chains and of one chain representing a V lambda 2----J lambda 3 rearrangement. Together with the previously determined sequence of the lambda 2 chain from myeloma MOPC-315, the results illustrate the following types of variable-region diversification: expression of a single V gene segment with more than one J segment, variability at the V-J junction, and presumably, somatic mutation in V and in J. The extent of somatic diversification in these lambda 2 chains is limited, consistent with results obtained previously with lambda 1 chains.