Overview Only in eukaryotes pre-processed transcript = hnRNA Process capping 5' end login to view 4 more bullets 3' end login to view 3 more bullets some viruses can steal host cell caps so that the viral mRNA gets translated splicing process of intron removal mediated by the spliceosome composed of small nuclear ribonucleoproteins (snRNPs) login to view 2 more bullets alternative splicing one hnRNA can be spliced differently to produce different protein products this requires conserved sequences including login to view 2 more bullets mutations that create new splice sites (AG) in the middle of the intron can lead to login to view 2 more bullets Location occurs in nucleus after transcription only processed RNA is transported out of the nucleus