Sandbox Reserved 962: Difference between revisions
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In eukaryotic cells, the synthezise of mRNA is followed by a process of maturation. The best-known modifications are the polyadenylation, the splicing and the capping. The cap is important to the traduction initiation ; it allows the mRNA to be recognized by initiation factors. It is also necessary to keep the stability of the mRNA. | In eukaryotic cells, the synthezise of mRNA is followed by a process of maturation. The best-known modifications are the polyadenylation, the splicing and the capping. The cap is important to the traduction initiation ; it allows the mRNA to be recognized by initiation factors. It is also necessary to keep the stability of the mRNA. | ||
The capping is therefore an important step of the maturation. It consists in adding a 7-methylguanosine on the first nucleotide of the mRNA with a diphosphate bonding. {{clear}} | The capping is therefore an important step of the maturation. It consists in adding a 7-methylguanosine on the first nucleotide of the mRNA with a diphosphate bonding. {{clear}} | ||
The capping involved many steps: First the γ-phosphate from the 5′ end of the nascent RNA is removed. Then a GMP is transfered from GTP to the 5′-diphosphate creating the guanosine 5′-5′-triphosphate. After that, a methyl group is transfered from S-adenosylmethionine to the N7 position of the guanine and an other is transfered to 2′ oxygen of riboses at the 5′ end of the mRNA. | The capping involved many steps: First the γ-phosphate from the 5′ end of the nascent RNA is removed. Then a GMP is transfered from GTP to the 5′-diphosphate creating the guanosine 5′-5′-triphosphate. After that, a methyl group is transfered from S-adenosylmethionine to the N7 position of the guanine and an other is transfered to 2′ oxygen of riboses at the 5′ end of the mRNA. | ||
Ecm1 catalyses the transfer of the methyl group from S-adenosylmethionine to the N7 position of the guanine. This enzyme is a key enzyme in this capping process. {{clear}} | Ecm1 catalyses the transfer of the methyl group from S-adenosylmethionine to the N7 position of the guanine. This enzyme is a key enzyme in this capping process. {{clear}} | ||
[[Image:Cap.png]][[Image:Step_cap.png]] {{clear}} | |||
