PSF and p54nrb/NonO – multi‐functional nuclear proteins

Abstract

Proteins are often referred to in accordance with the activity with which they were first associated or the organelle in which they were initially identified. However, a variety of nuclear factors act in multiple molecular reactions occurring simultaneously within the nucleus. This review describes the functions of the nuclear factors PSF (polypyrimidine tract‐binding protein‐associated splicing factor) and p54^nrb/NonO. PSF was initially termed a splicing factor due to its association with the second step of pre‐mRNA splicing while p54^nrb/NonO was thought to participate in transcriptional regulation. Recent evidence shows that the simplistic categorization of PSF and its homolog p54^nrb/NonO to any single nuclear activity is not possible and in fact these proteins exhibit multi‐functional characteristics in a variety of nuclear processes.