Toti-type cap snatching

RNAs are capped during transcription by a unique viral reaction. m7GMP is cleaved from the 5'-end of host mRNAs that are covalently bound to the viral GTase. The m7GMP is then bound to a new transcribed viral ppRNA..

Since these viruses infect unicellular eukaryotes, no further methylation takes place as in multicellular eukaryotes (Cap-1). This mechanism of using a prefabricated mRNA cap has similarities with cellular trans-splicing described in nematodes, flatworms, cnidarians, ascidians, rotifers and euglenozoans .

Enzymatic reaction:
Host RNA decapping
Cap transfer