Sequence of Amino Acids of the NH₂‐Terminal Region of a Mouse‐Clonal Immunoglobulin Heavy Chain

The amino acid sequence of the cyanogen bromide fragments H 1 ‐H 3 from the γ chain of the plasmacytoma immunoglobulin MOPC 173 is reported. It represents the first 104 amino acid residues of this heavy chain, thus covering the major part of the V H region. This sequence allowed definition of a third subgroup of variability for the heavy chain pool, in common between mouse and human immunoglobulins.