Crp79p, like Mex67p, is an auxiliary mRNA export factor in Schizosaccharomyces pombe.
The export of mRNA from the nucleus to the cytoplasm involves interactions of proteins with mRNA and the nuclear pore complex. We isolated Crp79p, a novel mRNA export factor from the same synthetic lethal screen that led to the identification of spMex67p in Schizosaccharomyces pombe. Crp79p is a 710-amino-acid-long protein that contains three RNA recognition motif domains in tandem and a distinct C-terminus. Fused to green fluorescent protein (GFP), Crp79p localizes to the cytoplasm. Like Mex67p, Crp79-GFP binds poly(A)(+) RNA in vivo, shuttles between the nucleus and the cytoplasm, and contains a nuclear export activity at the C-terminus that is Crm1p-independent. All of these properties are essential for Crp79p to promote mRNA export. Crp79p import into the nucleus depends on the Ran system. A domain of spMex67p previously identified as having a nuclear export activity can functionally substitute for the nuclear export activity at the C-terminus of Crp79p. Although both Crp79p and spMex67p function to export mRNA, Crp79p does not substitute for all of spMex67p functions and probably is not a functional homologue of spMex67p. We propose that Crp79p is a nonessential mRNA export carrier in S. pombe.
Basic Research Laboratory, National Cancer Institute, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Anjan G
AG
Thakurta
William A
WA
Whalen
Jin Ho
JH
Yoon
Anekella
A
Bharathi
Libor
L
Kozak
Craig
C
Whiteford
Dona C
DC
Love
John A
JA
Hanover
Ravi
R
Dhar
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000595:Amino Acid Sequence; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007202:Indicators and Reagents / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000378:metabolism
C472813:Crp79 protein, S pombe; D007202:Indicators and Reagents; D008164:Luminescent Proteins; C106898:MEX67 protein, S cerevisiae; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D049452:Green Fluorescent Proteins; D020931:ran GTP-Binding Protein