Constancy of amino-terminal amino-acid sequences of antibodies of defined specificity and shared idiotype from individual inbred mice.

Amino-terminal amino-acid sequences were determined for the heavy (H) chains of anti-p-azophenylarsonate antibodies with shared idiotype, isolated from nine individual A/J mice. Mice chosen for investigation were those producing high titers of antibody with the cross-reactive idiotype. The antibodies were further enriched for the idiotype by isoelectric focusing. The H chains are largely or entirely unblocked at the N-terminus and appear by sequence analysis to be greatly restricted in heterogeneity. All N-terminal sequences were found to be identical. The results suggest that the framework (nonhypervariable) sequence is determined by a germ line gene and is not influenced by somatic processes.