Determination of the Primary Structure of a Mouse IgG2a Immunoglobulin: Amino-Acid Sequence of the Fc Fragment.

The amino-acid sequence of the Fe fragment of a mouse monoclonal IgG2a molecule is presented. With the exception of one deletion, this region possesses the same length as that of the human γl chain or that of the rabbit γ chain. Identities between the Fc fragments of 3 animal species (human, mouse and rabbit) average 50% and are markedly more pronounced for the C_H2 domain than for the C_H3 domain, observation which is in agreement with an independent evolution of each homology region. Strikingly, the degree of conservation of the V_H region is of the same order of magnitude as that observed for the Fc fragment. This parallelism in evolution is discussed. [ABSTRACT FROM AUTHOR]