Viral Polymerase vRNA (Genomic):NP Complex vRNA Transcription Complex Mature intronless transcript derived mRNA Assembly of an Active Transcription Complex Authored: Bortz, E, Garcia-Sastre, A, 2007-02-12 19:39:05 GENE ONTOLOGYGO:0019083 Pubmed10526235 Pubmed12072510 Pubmed15134462 Pubmed15827195 Pubmed283399 Pubmed6261960 Pubmed7769657 Pubmed9755184 Reactome Database ID Release 43168326 Reactome, http://www.reactome.org ReactomeREACT_6142 Reviewed: Squires, B, 2007-02-12 19:39:22 The 5' end of the vRNA associates with a binding site on the PB1 subunit of the viral RNA polymerase, distinct from the 3' vRNA binding site, which is subsequenty bound forming a loop. These binding events set off allosteric conformational changes in the trimeric polymerase complex that induce PB2 binding of the methylated cap on a host pre-mRNA (Plotch, 1981; Cianci, 1995; Li, 1998; Brownlee, 2002; Kolpashchikov, 2004). PB2 amino acids 242-282 and 538-577 are involved in cap binding (Honda, 1999). Direct or indirect interaction with active, transcribing host RNA polymerase II is thought to supply host mRNA for the caps (Bouloy, 1978; Engelhardt, 2005).