Variable region correlates of group b allotypes: amino acid sequence studies of b9 L chains from homogeneous antibodies.

The amino acid sequence was determined for residues for residues 1 to 88 and residues 110 to 147 for a rabbit light chain (4153-I) with allotype b9 from a homogeneous anti-streptococcal antibody. The amino acid sequence of the L chain from a second antibody (4153-II) was also determined for residues 1 to 49 and 62 to 77. In spite of the large differences in constant region sequence between b4 and b9 L chains, the variable regions of these antibodies are quite similar to those reported for b4 L chains. Both chains bear a b9-specific substitution (glutamic acid) at position 16. The 4153-I chain also has substitutions at positions 70 and 81 that may be exclusive to variable regions of the L chains with the b9 allotype. These allotype-associated VL structural differences offer support to the notion that structural genes for the CL region are either linked to distinct VL gene complexes or that certain V regions are expressed only in concert with certain CL regions.