Adenovirus E1a Gene Product Expressed at High Levels in Escherichia coli Is Functional

The human type C adenovirus E1a 13S messenger RNA encodes a gene product, that positively regulates the transcription of viral genes and certain cellular genes and is involved in the transformation of primary mammalian cells. The E1a gene product was expressed at high levels in Escherichia coli. In a Xenopus oocyte microinjection assay, the purified Escherichia coli-produced protein activated the E1a-responsive adenovirus E3 promoter and functioned as efficiently as the E1a gene itself.