UNCLEAVED ENV GP160 OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 IS DEGRADED WITHIN THE GOLGI-APPARATUS BUT NOT LYSOSOMES IN COS-1 CELLS

The fate of newly synthesized human immunodeficiency virus type 1 env gp160 was examined in COS-1 cells. The results of morphological chase experiments involving cycloheximide demonstrated that gp160 was retain ed in the Golgi apparatus for longer than the half-life of the molecul e. The degradation of gp160 was insensitive to both bafilomycin A(1) a nd leupeptin (<0.2 mM), which block lysosomal proteolysis. However, de gradation was effectively suppressed by leupeptin at higher concentrat ions, maximally at 1.7 mM. Furthermore, undegraded gp160 was accumulat ed in the Golgi apparatus, but was not detected in lysosomes. These re sults indicate that in COS-I cells gp160 is not degraded in lysosomes, but rather that degradation takes place in the Golgi apparatus.