Gene expression and structure of immunoglobulin epsilon chains.

The study of immunoglobulin genes has been an active area of research in recent years. The study of IgE heavy (epsilon) chain gene, in particular, has a significant impact on our understanding of the IgE system. The localization of the epsilon gene in the cluster of mouse heavy chain constant region genes has been determined, and models for gene rearrangements leading to epsilon chain gene expression have been provided. The regulation of IgE antibody production can thus be discussed in the context of these models in combination with knowledge of the cellular basis of IgE production. Comparison of the epsilon chain sequence among human, rat, and mouse has allowed a better understanding of the evolution and structure-function relationship of the epsilon chain. Furthermore, expression of epsilon chain cDNA in Escherichia coli and demonstration of biological activities of expression products have paved the basis for identification of defined peptides representing the structures for recognition by IgE receptors. These studies are discussed in this review.