RNA Guanylyltransferase And 5"-Phosphatase (RNGTT)

Addition of a 5-prime-terminal cap to eukaryotic mRNAs has important consequences for downstream events in gene expression. Caps are formed on nascent pre-mRNAs by the sequential action of RNA 5-prime-triphosphatase, which removes the gamma-phosphate on the initiating nucleotide; RNA guanylyltransferase, which transfers GMP from GTP to the resulting diphosphate end; and RNA (guanine-7) methyltransferase, which methylates the guanine N7 position of the newly formed GpppN termini.These authors also identified HCE1A and HCE1B, alternatively spliced mRNAs encoding proteins lacking part of the C-terminal region. The shorter isoforms possessed only RNA 5-prime-triphosphatase activity. HCE1, but not HCE1A or HCE1B, complemented S. cerevisiae ceg1 and cet1 mutations.