Previous Article | Next Article ![]()
Molecular and Cellular Biology, December 2000, p. 8996-9008, Vol. 20, No. 23
European Molecular Biology Laboratory,
D-69117 Heidelberg, Germany1; Institute
of Histology and Embryology, Faculty of Medicine, University of Lisbon,
1699 Lisbon Codex, Portugal2; and
Institute of Biochemistry, Swiss Federal Institute of
Technology, CH-8092 Zürich, Switzerland3
Received 12 July 2000/Returned for modification 15 August
2000/Accepted 6 September 2000
Vertebrate TAP (also called NXF1) and its yeast orthologue, Mex67p,
have been implicated in the export of mRNAs from the nucleus. The TAP
protein includes a noncanonical RNP-type RNA binding domain, four
leucine-rich repeats, an NTF2-like domain that allows
heterodimerization with p15 (also called NXT1), and a
ubiquitin-associated domain that mediates the interaction with
nucleoporins. Here we show that TAP belongs to an evolutionarily
conserved family of proteins that has more than one member in higher
eukaryotes. Not only the overall domain organization but also residues
important for p15 and nucleoporin interaction are conserved in most
family members. We characterize two of four human TAP homologues and
show that one of them, NXF2, binds RNA, localizes to the nuclear
envelope, and exhibits RNA export activity. NXF3, which does not bind
RNA or localize to the nuclear rim, has no RNA export activity.
Database searches revealed that although only one p15
(nxt) gene is present in the Drosophila
melanogaster and Caenorhabditis elegans genomes, there is at least one additional p15 homologue (p15-2 [also called NXT2]) encoded by the human genome. Both human p15 homologues bind
TAP, NXF2, and NXF3. Together, our results indicate that the TAP-p15
mRNA export pathway has diversified in higher eukaryotes compared to yeast, perhaps reflecting a greater substrate complexity.
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
TAP (NXF1) Belongs to a Multigene Family of
Putative RNA Export Factors with a Conserved Modular
Architecture
*
Corresponding author. Mailing address: EMBL,
Meyerhofstrasse 1, D-69117 Heidelberg, Germany. Phone: 0049 6221 387 389. Fax: 0049 6221 387 518. E-mail:
izaurralde{at}embl-heidelberg.de.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|