Identification and characterization of multiple conserved nuclear localization signals within adenovirus E1A.

The human adenovirus 5 (HAdV-5) E1A protein has a well defined canonical nuclear localization signal (NLS) located at its C-terminus. We used a genetic assay in the yeast Saccharomyces cerevisiae to demonstrate that the canonical NLS is present and functional in the E1A proteins of each of the six HAdV species. This assay also detects a previously described non-canonical NLS within conserved region 3 and a novel active NLS within the N-terminal/conserved region 1 portion of HAdV-5 E1A.

The adenovirus 55 residue E1A protein is a transcriptional activator and binds the unliganded thyroid hormone receptor.

The early region 1A (E1A) of human adenovirus types 2 and 5 is differentially spliced to yield five distinct mRNAs that encode different proteins. The smallest E1A RNA transcript encodes a 55 residue (55R) protein that shares only 28 amino acid residues with the other E1A proteins. Even though it is the most abundant E1A transcript at late times post-infection, little is known about the functions of this E1A isoform.