Characterization of an 11K protein produced by early region 3 of mouse adenovirus type 1.

Early region 3 (E3) of mouse adenovirus type 1 produces three mRNAs that can encode three proteins with unique carboxy-terminal exons. A bacterial fusion protein encoding the unique terminus of one the three predicted proteins was used to generate antiserum in rabbits. This antiserum detected a 14K protein on a Western blot of infected cell lysates. Immunoprecipitation and endoglycosidase H digestion revealed that the 14K protein was a glycoprotein with a core molecular weight of 11K, and we are designating this protein E3 gp 11K. Through in vitro translation experiments we determined that the previously predicted signal sequence of gp11K was cleaved when the protein was expressed during an infection. Biochemical and immunofluorescence microscopy data indicated that E3 gp11K was localized to the endoplasmic reticulum of infected cells. Biochemical experiments further indicated that gp11K is a peripheral membrane protein.