title: Immunoelectron microscopic studies of the intracellular transport of the membrane glycoprotein (G) of vesicular stomatitis virus in infected Chinese hamster ovary cells.
abstract: An immunoelectron microscopic study was undertaken to survey the intracellular pathway taken by the integral membrane protein (G-protein) of vesicular stomatitis virus from its site of synthesis in the rough endoplasmic reticulum to the plasma membrane of virus-infected Chinese hamster ovary cells. Intracellular transport of the G-protein was synchronized by using a temperature-sensitive mutant of the virus (0-45). At the nonpermissive temperature (39.8 degrees C), the G-protein is synthesized in the cell infected with 0-45, but does not leave the rough endoplasmic reticulum. Upon shifting the temperature to 32 degrees C, the G-protein moves by stages to the plasma membrane. Ultrathin frozen sections of 0-45-infected cells were prepared and indirectly immunolabeled for the G-protein at different times after the temperature shift. By 3 min, the G-protein was seen at high density in saccules at one face of the Golgi apparatus. No large accumulation of G-protein-containing vesicles were observed near this entry face, but a few 50-70-mm electron-dense vesicular structures labeled for G-protein were observed that might be transfer vesicles between the rough endoplasmic reticulum and the Golgi complex. At blebbed sites on the nuclear envelope at these early times there was a suggestion that the G-protein was concentrated, these sites perhaps serving as some of the transitional elements for subsequent transfer of the G-protein from the rough endoplasmic reticulum to the Golgi complex. By 3 min after its initial asymmetric entry into the Golgi complex, the G-protein was uniformly distributed throughout all the saccules of the complex. At later times, after the G-protein left the Golgi complex and was on its way to the plasma membrane, a new class of G-protein-containing vesicles of approximately 200-nm diameter was observed that are probably involved in this stage of the transport process. These data are discussed, and the further prospects of this experimental approach are assessed.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002472:Cell Transformation, Viral; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D008562:Membrane Glycoproteins; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000378:metabolism / Q000648:ultrastructure; D010053:Ovary; D014721:Vesicular stomatitis Indiana virus / Q000378:metabolism / Q000648:ultrastructure*; D014759:Viral Envelope Proteins; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014764:Viral Proteins