IDENTIFICATION AND ANALYSIS OF A NOVEL MEMBER OF THE UBIQUITIN FAMILYEXPRESSED IN DENDRITIC CELLS AND MATURE B-CELLS

Using a cDNA subtraction technique, a novel member of the ubiquitin fa mily was isolated from human dendritic cells. This gene encodes a diub iquitin 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 tonsill ar tissue showed expression in epithelial cells and isolated cells wit hin the germinal center. With respect to an expressed-sequence tag (ES T) this cDNA could be localized to the major histocompatibility comple x class I region of chromosome 6. Comparative analysis and the express ion pattern of this gene suggests a function in antigen processing and presentation.