Immortalization Up Regulated Protein (IMUP)

Database searches identified these genes on chromosome 19, which could account for the cloned imup-1 and imup-2 transcripts by alternative splicing. The expressed proteins IMUP-1 and IMUP-2 share 46 identical N-terminal amino acids, whereas the C-termini are unrelated. Green fluorescent protein-fusions of both IMUP-1 and IMUP-2 accumulated in the nucleus of HeLa cells. The C-terminus of IMUP-1 contains a bipartite nuclear localization signal, the deletion of which impaired nuclear translocation. In-vitro translated proteins bound to poly(rG), but did not interact with single-stranded DNA or double-stranded DNA. The nuclear localization of IMUP-1 and IMUP-2 as well as the upregulation of both underlying mRNAs in immortalized cells suggest a function in immortalization.