Intracellular transport of the murine leukemia virus during acute infection of NIH 3T3 cells: nuclear import of nucleocapsid protein and integrase.
The entry and intracellular transport of Moloney-murine leukemia virions inside mouse NIH 3T3 cells have been followed by electron microscopy techniques. Five viral proteins--matrix (MA, p15), capsid (CA, p30), nucleocapsid (NC, p10), integrase (IN), and the envelope glycoprotein (SU, gp70)--were located by immunolabeling using gold probes. After entering the cells, viral particles were frequently detected inside cytoplasmic vesicles of variable size. Their viral envelope was apparently lost during intracytoplasmic transport. When the unenveloped viral cores reached the nuclear membrane or its vicinity, they were disrupted. Two of the immunolabeled proteins, NC and IN, were detected entering the nucleus of non-dividing cells, where both were targeted to the nucleolus. However, MA and CA were found only in the cytoplasm. NC is a nucleic acid-binding protein which contains potential nuclear localization signals. We suggest that NC could enter the nucleus as part of a nucleoprotein complex, associated with IN, and possibly, also with viral DNA.
Risco
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Biological Carcinogenesis and Development Program, Program Resources, Inc./Dyncorp, Frederick, MD, USA.
Menéndez-Arias
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Copeland
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TD
Pinto da Silva
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P
Oroszlan
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S
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002213:Capsid / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D019426:Integrases; D007942:Leukemia, Experimental / Q000378:metabolism*; D051379:Mice; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008979:Moloney murine leukemia virus / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D012192:Retroviridae Infections / Q000378:metabolism*; D014412:Tumor Virus Infections / Q000378:metabolism*; D016662:Virus Integration
D009687:Nuclear Proteins; D004254:DNA Nucleotidyltransferases; D019426:Integrases