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Molecular and Cellular Biology, July 2001, p. 4219-4232, Vol. 21, No. 13
Institute of Microbiology, Centre Hospitalier
Universitaire Vaudois, 1012 Lausanne, Switzerland
Received 30 October 2000/Returned for modification 29 March
2001/Accepted 10 April 2001
Yra1p is an essential nuclear protein which belongs to the
evolutionarily conserved REF (RNA and export factor binding proteins) family of hnRNP-like proteins. Yra1p contributes to mRNA export in vivo and directly interacts with RNA and the shuttling mRNP export receptor Mex67p in vitro. Here we describe a second nonessential Saccharomyces cerevisiae family member, called
Yra2p, which is able to complement a YRA1 deletion when
overexpressed. Like other REF proteins, Yra1p and Yra2p consist of
two highly conserved N- and C-terminal boxes and a central RNP-like
RNA-binding domain (RBD). These conserved regions are separated
by two more variable regions, N-vr and C-vr. Surprisingly, the deletion
of a single conserved box or the deletion of the RBD in Yra1p
does not affect viability. Consistently, neither the conserved N and C
boxes nor the RBD is required for Mex67p and RNA binding in
vitro. Instead, the N-vr and C-vr regions both interact with Mex67p and
RNA. We further show that Yra1 deletion mutants which poorly interact with Mex67p in vitro affect the association of Mex67p with mRNP complexes in vivo and are paralleled by poly(A)+ RNA export
defects. These observations support the idea that Yra1p promotes
mRNA export by facilitating the recruitment of Mex67p to the mRNP.
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.13.4219-4232.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
The Yeast hnRNP-Like Proteins Yra1p and Yra2p
Participate in mRNA Export through Interaction with
Mex67p
*
Corresponding author. Mailing address: Institute of
Microbiology, Centre Hospitalier Universitaire Vaudois, 44 Rue du
Bugnon, 1011 Lausanne, Switzerland. Phone: 41 21 314 40 84. Fax: 41 21 314 40 95. E-mail: fstutz{at}hola.hospvd.ch.
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