4th International AIDS Conference Stockholm, Sweden. — June 12-16, 1988

Int Conf AIDS. 1988 Jun 12-16;4:1.115 (abstract no. 1011)

MA Rey, B Krust, L Montagnier, AG Hovanessian
Unité d'Oncologie Virale, Institut Pasteur Paris, France.

Four glycoproteins of apparent molecular weights 300,000, 140,000 , 125,000 and 36,000 (gp300, gp140, gp125 and gp36) are detectable in HIV-2 infected T4-antigen positive cells. The gp125 and gp36 are the external and transmembrane components of the envelope glycoproteins of HIV-2 mature virions. The gp300 and gpl40 are only detectable in virus-infected cells. They have identical isoelectric points in the pH range of 7.0 to 7.5, thus suggesting that gp300 might be a doublet form of the immature precursor, qp140. This doublet is probably formed by covalent associations since it is stable in the presence of ionic and non-ionic detergents, reducing agents, high salt and 4M urea. Pulse chase experiments indicate that gp300 is formed immediately after synthesis of gp140 and that this step is necessary for further processing towards the mature glycoproteins (see the schema below). These results were confirmed using various inhibitors which act at different stages in the glycosylation cycle of proteins;

gp140 → gp300 → 2 (gp125 + gp36)

A 300 KDa glycoprotein is also detectable in SIV-infected cells in addition to a 140 KDa glycoprotein precursor. In contrast, such a high molecular weight glycoprotein is not found in,HIV-1 infected cells. Therefore, doublet-formation of the envelope glycoprotein precursor seems to be a specific property of HIV-2 and SIV gene expression. The gp300 formation might be required for oligosaccharide trimming of HIV-2 glycoprotein precursor through the golgi apparatus.

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