Identification and gene mapping of a 14,700-molecular-weight protein encoded by region E3 of group C adenoviruses.

Early region E3 of adenovirus type 5 should encode at least nine proteins as judged by the DNA sequence and the spliced structures of the known mRNAs. Only two E3 proteins have been proved to exist, a glycoprotein (gp19K) and an 11,600-molecular-weight protein (11.6K protein). Here we describe an abundant 14.7K protein coded by a gene in the extreme 3' portion of E3. To identify this 14.7K protein, we constructed a bacterial vector which synthesized a TrpE-14.7K fusion protein, then we prepared antiserum against the fusion protein. This antiserum immunoprecipitated the 14.7K protein from cells infected with adenovirus types 5 and 2, as well as with a variety of E3 deletion mutants. Synthesis of the 14.7K protein correlated precisely with the presence or absence of the 14.7K gene and with the synthesis of the mRNA (mRNA h) which encodes the 14.7K protein. The 14.7K protein appeared as a triplet on immunoprecipitation gels and Western blots (immunoblots).