PSEUDOURIDINE FORMATION IN SMALL NUCLEAR RNAS

Recent in vitro studies on the formation of pseudouridine (Psi) in the spliceosomal small nuclear RNAs (snRNA) are reviewed. Multiple Psi sy nthase activities, in some cases more that one per snRNA, are responsi ble for this modification of uridine. There is a requirement for Sm pr otein binding for the efficient formation of Psi in U5 RNA but not for the modification of U2 RNA. The inhibition of Psi formation by the in corporation of 5-fluorouridine in the snRNA is also reviewed.