Binding of Arenavirus to the Transferrin Receptor TfR1. The dimeric transferrin receptor is expressed on the cell surface (1). Upon binding of diferric transferrin or the virus to TfR1, the receptor complex is endocytosed and fuses with the endosome (2). The low pH of the endosome allows the virus release from the receptor, much the same as the release of transferrin and iron (3). TfR1 and apo-transferrin are then able to be recycled to the membrane for additional rounds of iron acquisition. the low pH facilitates dissociation of GP1 viral coat proteins from the virus. The virus is then free to interact with the endosomal membrane (4). Fusion of the endosomal and viral membranes occurs and release of the bisegmented RNA genome into the host cell completes the process of infection (5).