FURIN IS IMPORTANT BUT NOT ESSENTIAL FOR THE PROTEOLYTIC MATURATION OF GP160 OF HIV-1

The envelope glycoproteins of HIV are required for viral infectivity. Proteolgsis of the Precursor envelope glycoprotein gp160 results in th e formation of gp120 acid gp41. Cleavage occurs after the sequence Arg -Glu-Lys-Arg. This sequence is expected to be a substrate for the cell ular protease furin. We examined whether furin is responsible for clea vage of gp160 by using a furin-deficient CHO cell line and the same ce ll line transfected with furin cDNA. Data obtained from viral transmis sion assays suggested that furin increased viral infectivity but was n ot essential for the maturation of gp160, implying that other proprote in processing enzymes also recognize this putative furin cleavage site .