Multiple related immunoglobulin variable-region genes identified by cloning and sequence analysis.

Abstract

At least 6 EcoRI fragments of mouse DNA that encode variable-region gene sequences closely related to the mouse .kappa. light chain, MOPC-149 were identified. Two fragments were cloned, and the entire nucleotide sequence of the variable-region genes encoded on each was determined. Both genes encode closely related variable-region sequences extending from codon position 1 through position 97. Neither fragment encodes a constant-region sequence. Although both genes are closely related, they differ from one another and from the sequence expressed in the MOPC-149 cell from which they were cloned. These few differences cluster within the complementarity-determining regions although several occur in framework sequences as well. An antibody-producing cell contains genetic information corresponding to its expressed sequence and several other closely related but silent sequences. Similar sets of genes might exist corresponding to each of the many subgroups already identified among mouse .kappa. light chains. The mouse genome might be rich enough in variable-region genes so as to encode a major portion of the variable-region repertoire.