FUNCTIONAL DISSECTION OF THE MOLONEY MURINE LEUKEMIA-VIRUS ENVELOPE PROTEIN GP70

The envelope protein of Moloney murine leukemia virus (Mo-MLV) is a co mplex glycoprotein that mediates receptor binding and entry via fusion with cell membranes, By using a series of substitution mutations and truncations in the Mo-MLV external envelope surface protein gp70, we h ave identified regions important for these processes, Firstly, truncat ions of gp70 revealed that the minimal continuous receptor-binding reg ion is amino acids 9 to 230, in broad agreement with other studies, Se condly, within this region there are two key basic amino acids, Arg-83 and Arg-95, that are essential for receptor binding and may interact with a negatively charged residue(s) or with the pi electrons of the a romatic ring on a hydrophobic residue(s) in the basic amino acid trans porter protein that is the Mo-MLV ecotropic receptor, Finally, we show ed that outside the minimal receptor-binding region at amino acids 2 t o 8, there is a region that is essential for postbinding fusion events .