Identification and cloning of a novel chromatin-associated protein partner of Epstein-Barr nuclear protein 2

In a screen for binding partners of the Epstein-Barr virus transformation-related protein EBNA2, we cloned a novel, evolutionarily conserved protein showing similarity to the Drosophila Parallel Sister Chromatids Protein (PASC). We have named this protein "Friend of EBNA2" (FOE). Human FOE encodes a protein of 1227 amino acids with a functional bipartite nuclear localization signal, an arginine-rich motif, a putative nuclear export signal as well as with three highly acidic regions and a predicted coiled-coil domain. FOE and EBNA2 coimmunoprecipitate from lymphocyte nuclear extracts. RNA and protein blots show that FOE is expressed in all human tissues. FOE is a nuclear protein with the bulk of the protein associated with the insoluble nuclear fraction biochemically defined as the nuclear matrix. Indirect immunofluorescence and dynamic imaging studies suggest that FOE associates with transcriptionally active nuclear subregions in interphase cells and concentrates at the ends of formed chromosomes during mitosis.