A karyophilic signal sequence in adenovirus type 5 E1A is functional in Xenopus oocytes but not in somatic cells.

The carboxy-terminal five amino acids of the adenovirus type 5 E1A gene product are necessary and sufficient for this protein to become localized in the nuclei of somatic cells. In this report, we demonstrate that E1A contains a second nuclear localization signal, which resides within residues 140 to 185 and which functions in Xenopus oocytes but not Xenopus or mammalian somatic cells. These data demonstrate the cell-type-specific utilization of a nuclear localization signal.