Final answer:
The guanylyl transferase enzyme facilitates the reaction between the 5' phosphate of the first nucleotide and the α phosphate of GTP.
Step-by-step explanation:
The guanylyl transferase enzyme carries out the reaction between the 5' phosphate of the first nucleotide and the α phosphate of GTP (guanosine triphosphate).
In many biological reactions, enzymes like guanylyl transferase catalyze the transfer of phosphate groups. For instance, during the process of mRNA capping in eukaryotes, guanylyl transferase attaches a GTP molecule to the 5' end of the RNA transcript. The enzyme facilitates the formation of a 5' to 5' triphosphate linkage, utilizing the α-phosphate of the GTP and the 5' phosphate of the RNA. This cap structure is crucial as it enhances mRNA stability, facilitates mRNA export from the nucleus, and is involved in the initiation of translation.