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).
Krystal, M, Tiley, L, Cianci, C
Honda, A, Mizumoto, K, Ishihama, A
Sharps, JL, Brownlee, GG
Krug, RM, Ramirez, BC, Li, ML
Plotch, SJ, Krug, RM, Bouloy, M, Ulmanen, I
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