The amino acid sequence of the variable regions of the light chains from two idiotypically cross reactive IgM anti-gamma globulins.

Amino acid sequence analysis of the light chains of two IgM rheumatoid factors is presented. The parent molecules of these chains are human IgM proteins with specificity for human IgG and sharing idiotypic cross reactivity. The heavy chains had previously been shown to have extremely similar hypervariable regions. This communication presents data indicating that the light chains, even though representing two different kappa subgroups, also share identities in their hypervariable regions. These data can be most easily interpreted in terms of a gene interaction model for immunoglobulin V region assembly.