A. Bhattacharya et al., Characterization of the biochemical properties of the human Upf1 gene product that is involved in nonsense-mediated mRNA decay, RNA, 6(9), 2000, pp. 1226-1235
The Upf1 protein in yeast has been implicated in the modulation of efficien
t translation termination as well as in the accelerated turnover of mRNAs c
ontaining premature stop codons, a phenomenon called nonsense-mediated mRNA
decay (NMD). A human homolog of the yeast UPF1, termed HUpf1/RENT1, has al
so been identified. The HUpf1 has also been shown to play a role in NMD in
mammalian cells. Comparison of the yeast and human UPF1 proteins demonstrat
ed that the amino terminal cysteine/histidine-rich region and the region co
mprising the domains that define this protein as a superfamily group I heli
case have been conserved. The yeast Upf1p demonstrates RNA-dependent ATPase
and 5' --> 3' helicase activities. In this paper, we report the expression
, purification, and characterization of the activities of the human Upf1 pr
otein. We demonstrate that human Upf1 protein displays a nucleic-acid-depen
dent ATPase activity and a 5' --> 3' helicase activity. Furthermore, human
Upf1 is an RNA-binding protein whose RNA-binding activity is modulated by A
TP. Taken together, these results Indicate that the activities of the Upf1
protein are conserved across species, reflecting the conservation of functi
on of this protein throughout evolution.