Molecular and Cellular Biology, March 1999, p. 2212-2219, Vol. 19, No. 3
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.

Centro Nacional de Biotecnología (CSIC), Cantoblanco, 28049 Madrid, Spain,1 and European Molecular Biology Laboratory, 69012 Heidelberg, Germany2
Received 27 May 1998/Returned for modification 7 July 1998/Accepted 11 September 1998
In the course of a two-hybrid screen with the NS1 protein of
influenza virus, a human clone capable of coding for a protein with
high homology to the Staufen protein from Drosophila
melanogaster (dmStaufen) was identified. With these sequences
used as a probe, cDNAs were isolated from a
cDNA library. The
encoded protein (hStaufen-like) contained four double-stranded RNA
(dsRNA)-binding domains with 55% similarity and 38% identity to those
of dmStaufen, including identity at all residues involved in RNA
binding. A recombinant protein containing all dsRNA-binding domains was
expressed in Escherichia coli as a His-tagged polypeptide.
It showed dsRNA binding activity in vitro, with an apparent
Kd of 10
9 M. Using a specific
antibody, we detected in human cells a major form of the hStaufen-like
protein with an apparent molecular mass of 60 to 65 kDa. The
intracellular localization of hStaufen-like protein was investigated by
immunofluorescence using a series of markers for the cell compartments.
Colocalization was observed with the rough endoplasmic reticulum but
not with endosomes, cytoskeleton, or Golgi apparatus. Furthermore,
sedimentation analyses indicated that hStaufen-like protein associates
with polysomes. These results are discussed in relation to the possible
functions of the protein.
Present address: European Molecular Biology Laboratory, 69012 Heidelberg, Germany.
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