Translation of glucose-regulated protein 78/immunoglobulin heavy-chain binding protein mRNA is increased in poliovirus-infected cells at a time when cap-dependent translation of cellular mRNAs is inhibited.
All cellular cytoplasmic mRNAs carry a 7-methylguanylate cap attached to their 5' ends. This cap structure is recognized by cap-binding proteins that then direct the binding of ribosomal subunits to this 5'-end complex. Poliovirus, a plus-stranded RNA virus, interferes with this cellular translation process by proteolytically inactivating the cap-binding protein complex. Subsequently the viral mRNA can be translated by an initiation process in which ribosomes bind internally to the mRNA [Pelletier, J. & Sonenberg, N. (1988) Nature (London) 334, 320-325], obviating cap-dependent translation. At least one cellular mRNA, encoding a heat shock-like protein, glucose-regulated protein 78/immunoglobulin heavy-chain binding protein, has been discovered to be translated at an increased rate in poliovirus-infected cells at a time when the translation of other cellular mRNAs is inhibited. The glucose-regulated protein 78/immunoglobulin heavy-chain binding protein mRNA thus exemplifies a cellular mRNA that is translated at a specifically enhanced rate by an as-yet-unresolved cap-independent initiation process in cells when the cap-binding protein complex is not functional.
Sarnow
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Department of Biochemistry, University of Colorado Health Sciences Center, Denver 80262.
D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D002472:Cell Transformation, Viral; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D000091342:Endoplasmic Reticulum Chaperone BiP; D006367:HeLa Cells / Q000378:metabolism; D006360:Heat-Shock Proteins; D006801:Humans; D018832:Molecular Chaperones; D008970:Molecular Weight; D017955:Poliovirus / Q000235:genetics*; D014176:Protein Biosynthesis; D012315:RNA Caps / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D012315:RNA Caps; D012333:RNA, Messenger