TRANSFER OF ENDOPLASMIC-RETICULUM AND GOLGI RETENTION SIGNALS TO HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 GP160 INHIBITS INTRACELLULAR-TRANSPORTAND PROTEOLYTIC PROCESSING OF VIRAL GLYCOPROTEIN BUT DOES NOT INFLUENCE THE CELLULAR SITE OF VIRUS PARTICLE BUDDING

In this study, specific signals known to mediate endoplasmic reticulum or Golgi localization of transmembrane proteins have been transferred to the human immunodeficiency virus type 1 (HIV-1) env gene product. The intracellularly retained recombinant glycoproteins were not proteo lytically processed to gp120 and gp41, which is further evidence that this process occurs at a later stage in the transport pathway, presuma bly within or near the trans-Golgi network. Since the subcellular loca lization of the viral glycoproteins of enveloped viruses can be one of the factors determining the cellular site of particle assembly and re lease, experiments were performed to determine if this property was al tered by coexpression of the recombinant HIV-1 glycoproteins. When wil d-type virus was compared to mutant virus encoding the intracellularly retained glycoproteins, the extent of HIV-1 into the extracellular me dium unaffected, and electron-microscopic analysis did not reveal any significant alteration in the cellular sites of particle assembly and budding. Thus, in COS-7 cells, altered subcellular localization of the viral glycoprotein does not exert a dominant influence on the assembl y site of the HIV-1 particle.