Swm2 (Synthetic With MUD-2-delta protein2) binds Tgs1, an enzyme responsible for 2,2,7-trimethylguanosine (TMG) capping of small nuclear (sn) RNAs implicated in pre-mRNA splicing [, , ]. Deletion of SWM2 impairs pre-mRNA splicing and ribosome biogenesis, exhibiting a similar phenotype to tgs1 mutant. Swm2 is required for trimethylation of spliceosomal snRNAs and the U3 snoRNA by Tgs1 [].