2 DISTINCT ONCORNAVIRUSES HARBOR AN INTRACYTOPLASMIC TYROSINE-BASED BASOLATERAL TARGETING SIGNAL IN THEIR VIRAL ENVELOPE GLYCOPROTEIN

It has been clearly established that the budding of the human immunode ficiency virus (HIV-1), a lentivirus, occurs specifically through tile basolateral membrane in polarized epithelial cells, More recently, th e signal was assigned to a tyrosine-based motif located in the intracy toplasmic domain of the envelope glycoprotein, as previously observed on various other viral and cellular basolateral proteins, In the prese nt study, expression of human T-cell leukemia virus type I (HIV-1) or Moloney murine leukemia visus envelope glycoproteins was used for tran s-complementation of an envelope-negative HIV-1. This demonstrated the potential of oncornaviral retrovirus envelope glycoproteins to confer polarized basolateral budding in epithelial Madin-Darby canine kidney cells (MDCK cells). Site-directed mutagenesis confirmed the importanc e afa common motif encompassing at least one crucial membrane-proximal intracytoplasmic tyrosine residue, The conservation of a similar baso lateral maturation signal in different retroviruses further supports i ts importance in the biology of this group of viruses.