E1B 55-kilodalton-associated protein: a cellular protein with RNA-binding activity implicated in nucleocytoplasmic transport of adenovirus and cellular mRNAs.
The adenovirus type 5 (Ad5) early 1B 55-kDa protein (E1B-55kDa) is a multifunctional phosphoprotein that regulates viral DNA replication and nucleocytoplasmic RNA transport in lytically infected cells. In addition, E1B-55kDa provides functions required for complete oncogenic transformation of rodent cells in cooperation with the E1A proteins. Using the far-Western technique, we have isolated human genes encoding E1B-55kDa-associated proteins (E1B-APs). The E1B-AP5 gene encodes a novel nuclear RNA-binding protein of the heterogeneous nuclear ribonucleoprotein (hnRNP) family that is highly related to hnRNP-U/SAF-A. Immunoprecipitation experiments indicate that two distinct segments in the 55-kDa polypeptide which partly overlap regions responsible for p53 binding are required for complex formation with E1B-AP5 in Ad-infected cells and that this protein interaction is modulated by the adenovirus E4orf6 protein. Expression of E1B-AP5 efficiently interferes with Ad5 E1A/E1B-mediated transformation of primary rat cells. Furthermore, stable expression of E1B-AP5 in Ad-infected cells overcomes the E1B-dependent inhibition of cytoplasmic host mRNA accumulation. These data suggest that E1B-AP5 might play a role in RNA transport and that this function is modulated by E1B-55kDa in Ad-infected cells.
Gabler
S
S
Institut für Medizinische Mikrobiologie und Hygiene, Universität Regensburg, D-93053 Regensburg, Germany.
Schütt
H
H
Groitl
P
P
Wolf
H
H
Shenk
T
T
Dobner
T
T
D000256:Adenoviridae / Q000235:genetics*; D017501:Adenovirus E1B Proteins / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D018076:DNA, Complementary; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D051381:Rats; D017386:Sequence Homology, Amino Acid
D017501:Adenovirus E1B Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins