Identification and analysis of a novel member of the ubiquitin family expressed in dendritic cells and mature B cells

Abstract Using a cDNA subtraction technique, a novel member of the ubiquitin family was isolated from human dendritic cells. This gene encodes a diubiquitin protein containing tandem head to tail ubiquitin‐like domains, with the conservation of key functional residues. Expression of this 777‐bp mRNA was restricted to dendritic cells and B cells, with strong expression in mature B cells. Southern blot analysis indicated that a single copy of this gene is present. In situ hybridization on tonsillar tissue showed expression in epithelial cells and isolated cells within the germinal center. With respect to an expressed‐sequence tag (EST) this cDNA could be localized to the major histocompatibility complex class I region of chromosome 6. Comparative analysis and the expression pattern of this gene suggests a function in antigen processing and presentation.