T4-LYMPHOCYTE ENDOPROTEASE RESPONSIBLE FOR THE PROTEOLYTIC PROCESSINGOF HIV-1 GP160, LIKE KEX2P ENDOPROTEASE, IS A CALCIUM-DEPENDENT ENZYME

In the present study we show that precursor gp160 is cleaved in the HI V-1 infected CEM (CD4(+)) cell line preferentially in the presence of calcium ions demonstrating that the responsible cellular endoprotease is a calcium-dependent enzyme. Taking into account this similarity, a synthetic peptide modelling the cleavage site of HIV-1 envelope glycop rotein precursor was used as substrate for Kex2p. Results obtained cle arly showed that the processing enzyme Kex2p (EC 3.4.21.61), a subtili sin-like serine protease that is encoded by the KEX2 gene of yeast Sac charomyces cerevisiae is able to cleave correctly this peptide at the potential cleavage site.