Comparative study on the structure of the light chains of human immunoglobulins. II. Assignment of a new subgroup.

The primary structure of the variable region of the human lambda type Bence Jones protein NIG-48 was determined by analysis of the N-terminal sequence of the completely reduced and aminoethylated protein, as well as of five cyanogen bromide fragments. The variable region of NIG-48 contains 112 amino acid residues. The protein NIG-48, having a unique sequence of the variable region, a low degree of homology (about 50%) with lambda chains of the five other subgroups and the addition of two residues around 65, may represent a new subgroup, namely V lambda VI.