Intracellular localization of JSRV Env proteins. Confocal microscopy of 293T cells transiently transfected with the empty expression vector pCDNA 3.1 (A), the HA-tagged full-length expression plasmid ΔGPHA (B), the HA-tagged SU deletion construct ΔGP SUΔ103-352HA, ΔGP SUΔ103-402HA, ΔGP SUΔ253-302HA, or ΔGP SUΔ353-402HA (C, D, E, and F, respectively), or the HA-tagged SU Env PstI insertion construct ΔGP SU102/103PstIHA (G) is shown. HA-tagged Env proteins were detected by staining with a fluorescein isothiocyanate-conjugated monoclonal antibody to HA. Bar, 2 μm. Magnification, ×600.