title: Retargeting of viral glycoproteins into a non-exporting compartment during the myogenic differentiation of rat L6 cells.
abstract: We have analysed protein trafficking during the differentiation of rat L6 myoblasts into myotubes. Different proteins were found to lose different amounts of their processing by the Golgi apparatus during the myogenic differentiation, indicating that they were transported to this organelle with differing efficiencies. In order to investigate the destination of the nonprocessed glycoproteins we analysed the behaviour of vesicular stomatitis virus (VSV) and Semliki Forest virus glycoproteins in the presence of Brefeldin A, which returns the enzymes of the Golgi apparatus to the ER. Such experiments indicated that during myogenesis a fraction of both glycoproteins was shunted into a compartment that did not participate recycling with the Golgi apparatus. Immunofluorescence studies with the mutant VSV tsO45 G protein suggested that this compartment was diffusively distributed. We investigated whether the cytoplasmic tail had a role in the myogenic transport modulation by analysing the behaviour of recombinant VSV G proteins. Exchanging the cytoplasmic tail or the tail plus the membrane anchor had no effect, suggesting that the luminal portion was responsible for the diverted transport. Taken together, the results suggest that during the myogenesis of L6 myoblasts, varying fractions of different viral glycoproteins were sorted from the ER into a specific compartment that did not recycle with the Golgi apparatus.
authors.affiliation: Department of Anatomy and Cell Biology, University of Oulu, P.O. Box 5000, 90014 University of Oulu, Finland.
authors.forename: Tuula
authors.initials: T
authors.lastname: Kaisto
authors.forename: Veera
authors.initials: V
authors.lastname: Luukela
authors.forename: Elli
authors.initials: E
authors.lastname: Birr
authors.forename: Kalervo
authors.initials: K
authors.lastname: Metsikkö
mesh_terms: D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002451:Cell Compartmentation / Q000502:physiology*; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000493:pharmacokinetics*; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D051381:Rats; D013696:Temperature; D014759:Viral Envelope Proteins / Q000493:pharmacokinetics*; D014760:Viral Fusion Proteins / Q000493:pharmacokinetics*
chemical_list: C028391:G protein, vesicular stomatitis virus; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D011500:Protein Synthesis Inhibitors; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D020126:Brefeldin A