mRNA triphosphatase Cet1-like (IPR004206)

Short name: mRNA_triPase_Cet1

Overlapping homologous superfamilies

Domain relationships



The mRNA capping enzyme in yeast is composed of two subunits, alpha and beta. The alpha subunit has guanylyltransferase activity, whilst the beta subunit is an RNA 5'-triphosphatase (RTPase) [PMID: 9345280]. This entry represents a domain found in the mRNA capping enzyme beta subunit Cet1. RTPase catalyzes the first step in the mRNA cap formation process, the removal of the gamma-phosphate of triphosphate terminated pre-mRNA. This activity is metal-dependent. The 5'-end of the resulting mRNA diphosphate is subsequently capped with GMP by RNA guanylytransferase, and then further modified by one or more methyltransferases. The mRNA cap-forming activity is an essential step in mRNA processing. The RTPases are not conserved among eukarya and this subgroup includes fungal and protozoal RTPases. The RTPase domain of the mimivirus RTPase-GTase fusion mRNA capping enzyme also belongs to this subgroup. The domain is related to the CYTH domain. Cet1 has a novel active site fold whereby an eight-strand beta-barrel forms a topologically closed tunnel known as the "triphosphate tunnel" [PMID: 16809816]. Enzymes with similar structures are able to bind triphosphorylated substrates and requiring divalent metal ions as activators. They were thus called triphosphate tunnel metalloenzymes (TTMs) [PMID: 24021036, PMID: 9755857, PMID: 10589681, PMID: 12788946, PMID: 11279161, PMID: 11395522, PMID: 11279098, PMID: 9710603, PMID: 12762032, PMID: 11051760, PMID: 12456267, PMID: 8418825].

Cetl paralogue, Ctl1 (capping enzyme RNAtriphosphatase-like 1), is a RNA 5'-triphosphatase probably involved in an RNA processing event other than mRNA capping [PMID: 10219091].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0004651 polynucleotide 5'-phosphatase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.