Adenovirus preterminal protein synthesized in COS cells from cloned DNA is active in DNA replication in vitro

Replication of the DNA genome of human adenovirus serotype 2 requires three virus-encoded proteins. Two of these proteins, the preterminal protein (pTP) and the adenovirus DNA polymerase, are transcribed from a single promoter at early times after virus infection. The mRNAs for these proteins share several exons, including one encoded near adenovirus genome coordinate 39. By using plasmids containing DNA fragments postulated to encode the various exons of pTP mRNA, the contributions of each exon to the synthesis of an active pTP have been measured. Only plasmids that contain both the open reading frame for pTP (genome coordinates 29.4 to 23.9) and the HindIII J fragment that contains the exon at genome coordinate 39 can express functional pTP.