Cloning and sequence analysis of the human major histocompatibility complex gene DC-3β

Abstract

The DC antigen is one of the class II major histocompatibility antigens involved in the regulation of the immune response. This molecule is a heterodimer composed of an α and a β chain. Southern blot analysis of several homozygous cell lines shows that there are two DCβ genes. The DC-3β gene, corresponding to a polymorphic restriction fragment, was cloned and sequenced and found to exist in five exons spanning 8 kilobase pairs of DNA. These exons correspond to the functional domains of the DCβ protein. Comparison of the β1 domains of known DCβ chains shows that the polymorphism is clustered in four regions. A similar comparison of the mouse Aβ sequences shows only two prominent diversity regions. The DCβ chain sequences are eight amino acids shorter than the Aβ chain sequences due to the elimination of a small exon by an aberrant spliceacceptor.