On the originn of antibody variability

Structure of Antibodies with Shared Idiotypy: The Complete Sequence of the Heavy Chain Variable Regions of Two Immunoglobulin M Anti-Gamma Globulins

“…Fig. 4 depicts the seven presently completed heavy chain variable region sequences from human myeloma proteins of the VHIII subgroup without known antibody activity (16,20,21). Proteins Lay and Pom are again displayed in this format.…”

Variation and Homology in the Mu and Gamma Heavy Chains of Human Immunoglobulins

“…The variable region (VHa) of each of these four heavy chains (one Au and three yl) is of the V1111 subgroup (8) and shares only about 45 percent identity in amino acid sequence with the variable region of Nie, which is of the VHIII subgroup (13), and only about 30 percent identity with the variable region of Eu, which is of the V1IT subgroup (12). In contrast, all four yl heavy chains are believed to have an identical amino acid sequence for all but one (or possibly two) of the 332 residues in their constant regions.…”

“…This is illustrated by the sequence Asp-Thr-Ala-Thr-Tyr-Tyr-Cys-Ala-Arg, which concludes the first 100 residues of the Ou ,u chain. An identical sequence is present at the corresponding positions in the Daw and Cor yl chains (5); only one residue differs in the human )yl chain Nie (13), in the rabbit y chain (16), and in the mouse (MOPC-173) y2a chain (17). Even the human yl chain Eu (12), which is of subgroup VHI, is identical at two-thirds of the positions in this short sequence.…”

Amino acid sequence of the VH region of human myeloma cryoimmunoglobulin IgG Hil

“…A comparison of the amino acid sequence of VH Hil with other human VH region sequences shows that VH Hil belongs to the VHIII subgroup of human immunoglobulins. A detailed comparison with protein Nie, a typical representative of this subgroup (Ponstingl et al, 1970), shows that 92 out of 121 residues are identical in both proteins (76%). Of the remaining 29 residues, 20 can be accommodated by a single-base change.…”