Sequence variations in b9 light chains as potential V region genetic markers.

Amino terminal sequence analyses of b9 light chains from rabbit antibodies to streptococcal carbohydrate have revealed the presence of glutamic acid at position N16 of light chains of the VκIII length. Glutamic acid has not previously been reported at position N16 of any light chain. Quantitative analysis of N-terminal residues of light chains from non-immune b9 IgG samples suggests that glutamic acid is present as a minor component at position N16 in b9 light chains of the V III length. Length determinations for quantitation of subgroups of b9 light chains were carried out by quantitative analysis on the sequencer and verified by determining the yield of PTH-2-14C-SCMC at each step. This refinement is possible because of the invariant cysteine at position N23 found in all light chains thus far sequenced. Sequence variations such as Glu at position N16 within light chains of a given subgroup can provide genetic markers for following the inheritance of the variable region of rabbit antibody light chains.