Abstract: |
Eukaryotic mRNAs contain a 5′-terminal cap structure consisting of a 7-methylguanosine residue linked to the end of the transcript via a 5′-5′ triphosphate bridge. The cap earmarks the mRNA for subsequent processing and nucleocytoplasmic transport, protects the mRNA from degradation and promotes efficient initiation of protein synthesis. A consilience of biochemistry, molecular genetics, and structural biology has illuminated the mechanism of cap synthesis. The expression, purification, and characterization of the proteins of various origins involved in the synthesis of the cap structure revealed that the physical and functional organizations of the capping apparatus differ in significant respects in fungi, metazoan, and viruses. It now appears that a selective inhibition of the enzymes involved in the synthesis of the cap structure could have important therapeutic applications. |