The carbotsal terminus domain is phosphorylated by transcription factor 2H. Elongation can now begin. The phosphorylated CTD allows for recruitment of proteins so splicing can begin as soon as the sequence is made. CTD recruits capin enzymes, splicing factors, and polyadenolation factors. The capin enzymes cap the pre and marina. Small nuclear ribonucleoprotein particles and splicing factor proteins make up the splice zone. U1 binds to the 5-pimes splice site and U2 binds the branch point site. The U4, 5, and 6 complex joins U1 and 2. U1 and U4 leave and the intron is spliced out. The etzons can now join together. The nucleosome pauses elongation so the splice zone can catch up. Faster splicing gives rise to increased accuracy of mature mRNA formation.