P72 - A HUMAN NUCLEAR DEAD BOX PROTEIN HIGHLY RELATED TO P68

P72, a novel human member of the DEAD box family of putative RNA-depen dent ATPases and ATP-dependent RNA helicases was isolated from a HeLa cDNA library, The predicted amino acid sequence of p72 is highly homol ogous to that of the prototypic DEAD box protein p68, In addition to t he conserved core domains characteristic of DEAD box proteins, p72 con tains several N-terminal RGG RNA-binding domains and a serine/glycine rich C-terminus likely involved in mediating protein-protein interacti ons. A p72-specific probe detects two mRNAs of approximately 5300 and 9300 bases which, although ubiquitously expressed, show variability in their expression levels in different tissues, Purified recombinant p7 2 exhibits ATPase activity in the presence of a range of RNA moieties, Immunocytochemical studies of p68 and p72 show that these proteins lo calise to similar locations in the nucleus of HeLa cells, suggesting t heir involvement in a nuclear process.