Does HIV NEF Protein Belong to the G-Protein Family?

Abstract

The nef gene (previously called F, 3 orf, or orf B) is one of the regulatory genes of HIV-1. It encodes a myristilated cytoplasmic protein migrating on an SDS-PAGE gel according to a molecular weight of 25 to 27 kDa (Allan et al., 1985 ; Franchini et al., 1986). It has been demonstrated that the Nef protein down regulates viral expression (Luciw et al., 1987), and more recently, it has been shown (Ahmad et al., 1988) that a cis-regulatory element located within the LTR (long terminal repeat) of HIV is responsive to Nef. This sequence has been mapped in the Negative Regulatory Element(s) (NRE) of the LTR (Rosen et al., 1985) and its presence has a negative effect on the synthesis of proteins expressed under the control of the HIV promoter. As Nef is a cytoplasmic protein which can be membrane associated, its presence in the nucleus is dubious. We thus have to imagine that Nef does not bind directly to the NRE and that it acts by the intermediate of a cellular pathway, like other signal transducing proteins. To investigate the biologicals properties of nef, we have expressed the Nef protein both in eukaryotic cell lines using recombinant vaccinia viruses (VVTGfHIV) and in E.coli in order to obtain the recombinant Nef protein in large quantities (Guy et al., 1987).