The human homologue of Saccharomyces cerevisiae Gle1p is required for poly(A)+ RNA export.
The mechanism of mRNA export is a complex issue central to cellular physiology. We characterized previously yeast Gle1p, a protein with a leucine-rich (LR) nuclear export sequence (NES) that is essential for poly(A)+ RNA export in Saccharomyces cerevisiae. To characterize elements of the vertebrate mRNA export pathway, we identified a human homologue of yeast Gle1p and analyzed its function in mammalian cells. hGLE1 encodes a predicted 75-kDa polypeptide with high sequence homology to yeast Gle1p, but hGle1p does not contain a sequence motif matching any of the previously characterized NESs. hGLE1 can complement a yeast gle1 temperature-sensitive export mutant only if a LR-NES is inserted into it. To determine whether hGle1p played a role in nuclear export, anti-hGle1p antibodies were microinjected into HeLa cells. In situ hybridization of injected cells showed that poly(A)+ RNA export was inhibited. In contrast, there was no effect on the nuclear import of a glucocorticoid receptor reporter. We conclude that hGle1p functions in poly(A)+ RNA export, and that human cells facilitate such export with a factor similar to yeast but without a recognizable LR-NES. With hGle1p localized at the nuclear pore complexes, hGle1p is positioned to act at a terminal step in the export of mature RNA messages to the cytoplasm.
Watkins
J L
JL
Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
Murphy
R
R
Emtage
J L
JL
Wente
S R
SR
D000595:Amino Acid Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D005800:Genes, Fungal; D006367:HeLa Cells; D006801:Humans; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D028861:Nuclear Pore Complex Proteins; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D005656:Fungal Proteins; C101408:GLE1 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins