Expression of the bovine papillomavirus type 1 E5B gene reveals a protein-protein interaction of the E5A and E5B gene products.
The bovine papillomavirus type 1 (BPV-1) genome has been shown to contain a small open-reading frame designated E5B (nucleotides 4013-4167) which is predicted to encode a hydrophobic, 52 amino acid protein. In order to detect and characterize the E5B protein, an 18 nucleotide sequence encoding a 6 amino acid epitope was added to the 3' end of the E5B open-reading frame which was then expressed in COS-1 cells using a SV40 vector. Immunoprecipitation, immunofluorescence, and cell fractionation studies identified the E5B protein as a 4-kDa protein and localized it primarily to membranes of the endoplasmic reticulum and nucleus. Unlike the E5A protein of BPV-1, E5B did not form dimers (despite containing a cysteine residue) or form complexes with growth factor receptors such as the PDGF receptor or erb B-2 receptor. Interestingly, the E5B protein formed physical complexes with the hydrophobic E5A oncoprotein, apparently via transmembrane interactions. Additionally, expression of E5B inhibited the transforming capability of BPV-1 E5A. These observations suggest that the expression of this viral protein may play a significant role in BPV/host cell interactions.
Wlazlo
A P
AP
Department of Pathology, Georgetown University Medical School, Washington, DC 20007, USA. wlazlo@wistar.upenn.edu
Sparkowski
J J
JJ
Jenson
A B
AB
Schlegel
R
R
D016475:3T3 Cells; D000818:Animals; D052688:Bovine papillomavirus 1 / Q000235:genetics*; D019556:COS Cells; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000939:Epitopes; D051379:Mice; D009685:Nuclear Envelope / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D016366:Open Reading Frames; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*
C081256:E5B protein, bovine papillomavirus 1; D000939:Epitopes; D009856:Oncogene Proteins, Viral; D014764:Viral Proteins; C054304:oncogene protein E5, Bovine papillomavirus type 1