InterPro domain: IPR044748

This entry represents the C-terminal methyltransferase domain of TARBP1 and Trm3 [ 1 ].

Yeast tRNA (guanosine(18)-2'-O)-methyltransferase Trm3 catalyses the formation of 2'-O-methylguanosine at position 18 (Gm18) in various tRNAs [ 2 ]. Trm3 is similar to C-terminal domain of TAR (HIV-1) RNA binding protein 1 (TARBP1), a protein binding to TAR, which functions as a RNA regulatory signal by forming a stable stem-loop structure to which transactivator protein Tat binds. The role of TARBP1 is believed to be to disengage RNA polymerase II from TAR during transcriptional elongation [ 3 , 4 ].

1. SPOUT: a class of methyltransferases that includes spoU and trmD RNA methylase superfamilies, and novel superfamilies of predicted prokaryotic RNA methylases. J. Mol. Microbiol. Biotechnol. 4, 71-5
2. The yeast Saccharomyces cerevisiae YDL112w ORF encodes the putative 2'-O-ribose methyltransferase catalyzing the formation of Gm18 in tRNAs. RNA 5, 66-81
3. Characterization of a human TAR RNA-binding protein that activates the HIV-1 LTR. Science 251, 1597-600
4. Crystal structure of the methyltransferase domain of human TARBP1. Proteins 72, 519-25