Molecular cloning and analysis of an eIF-4A-related rat liver nuclear protein.
In this paper, we report the cloning and analysis of a cDNA encoding a protein of M(r) congruent to 47,000 (p47), which is localized to the nucleus of rat hepatocytes. The cDNA showed 37% overall sequence identity with a mouse translation initiation factor, eIF-4A, which belongs to a family of putative ATP-dependent RNA helicases. We raised polyclonal antibodies against the fusion protein and by indirect immunofluorescence on primary cultures of hepatocytes have demonstrated that p47 is located in the nucleus. Although only approximately 27% of hepatocytes showed this nuclear staining, most of the nuclei in proliferating transformed cell lines such as 3T3, PtK-1, and Hela were fluorescently labeled. Studies on serum-starved cells in culture indicated that p47 was expressed in a cell cycle-dependent manner. Northern analyses demonstrated that the levels of p47 mRNA were high in fetal liver and dropped significantly after birth to low levels in adult liver. Our data suggest that p47 is developmentally regulated in rat liver at the mRNA level.
Nair
S
S
Department of Biological Sciences, State University of New York, Buffalo 14260.
Dey
R
R
Sanford
J P
JP
Doyle
D
D
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002453:Cell Cycle; D003001:Cloning, Molecular; D053487:DEAD-box RNA Helicases; D004247:DNA; D039601:Eukaryotic Initiation Factor-4A; D005260:Female; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D008099:Liver / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000302:isolation & purification; D010448:Peptide Initiation Factors / Q000235:genetics*; D011247:Pregnancy; D014176:Protein Biosynthesis; D051381:Rats; D015183:Restriction Mapping; D016415:Sequence Alignment
D009687:Nuclear Proteins; D010448:Peptide Initiation Factors; D004247:DNA; C075446:Ddx39b protein, rat; D039601:Eukaryotic Initiation Factor-4A; D053487:DEAD-box RNA Helicases