adapteritena translatsioonil polüpeptiidahelasse lülitatavate aminohapete ja mRNA molekulis asuvate aminohappeid määravate koodonite vahel. Ribosomaalsed RNA molekulid (rRNA) kuuluvad ribosoomide koostisesse. Väikesed tuuma RNA-d (snRNA molekulid small nuclear RNAs) osalevad intronite splaissingul. 25. mRNA protsessing mRNA processing The pre-mRNA molecule undergoes three main modifications. These modifications are 5' capping, 3' polyadenylation, and RNA splicing, which occur in the cell nucleus before the RNA is translated.[2] [edit]5' Processing Main article: 5' cap [edit]Capping Capping of the pre-mRNA involves the addition of 7-methylguanosine (m7G) to the 5' end. To achieve this, the terminal 5' phosphate requires removal, which is done with the aid of aphosphatase enzyme. The enzyme guanosyl transferase then catalyses the reaction, which produces the diphosphate 5' end. The diphosphate 5' prime end then attacks the gamma
adapteritena translatsioonil polüpeptiidahelasse lülitatavate aminohapete ja mRNA molekulis asuvate aminohappeid määravate koodonite vahel. Ribosomaalsed RNA molekulid (rRNA) kuuluvad ribosoomide koostisesse. Väikesed tuuma RNA-d (snRNA molekulid small nuclear RNAs) osalevad intronite splaissingul. 25. mRNA protsessing mRNA processing The pre-mRNA molecule undergoes three main modifications. These modifications are 5' capping, 3' polyadenylation, and RNA splicing, which occur in the cell nucleus before the RNA is translated.[2] [edit]5' Processing Main article: 5' cap [edit]Capping Capping of the pre-mRNA involves the addition of 7-methylguanosine (m7G) to the 5' end. To achieve this, the terminal 5' phosphate requires removal, which is done with the aid of aphosphatase enzyme. The enzyme guanosyl transferase then catalyses the reaction, which produces the diphosphate 5' end. The diphosphate 5' prime end then attacks the gamma
Kui RNAPolII on jõudnud sünteesida uuest transkriptist 25-30 nukleotiidi, siis 7- metüülguanosiin ja teised 5'cap komponendid on juba mRNAde 5' otsa küljes. Seda algset staadiumi RNA protsessingus katalüüsib dimeerne capping ensüüm, mis seostub RNAPolII fosforüülitud CTDga. In most protein-coding genes, a conserved AAUAAA poly(A) signal lies slightly upstream from a poly(A) site where cleavage and polyadenylation occur. A GU- or U rich sequence downstream from the poly(A) site contributes to the efficiency of cleavage and polyadenylation. A multiprotein complex that includes poly(A) polymerase (PAP) carries out the cleavage and polyadenylation of a pre-mRNA. A nuclear poly(A)-binding protein, PABPII, stimulates addition of A residues by PAP and stops addition once the poly(A) tail reaches 200250 residues. Küpse, funktsionaalse mRNA tekkimine hõlmab veel protsessi, mida nim
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