Biological and structural pleomorphism of the oncornavirus envelope glycoprotein, gp70.

It has been postulated that oncornaviruses play a role in development and differentiation, and that neoplasia is an unforunate consequence of an otherwise important symbiosis (Huebner and Todaro, 1969; Huebner et al., 1970). These concepts are attractive on a theoretical basis, but remained unproved. Nevertheless, the relationship between viral gene expression and normal host-cell functions has been studied in some detail, especially in the case of the interactions between the oncornaviruses and lymphoid cells of the mouse (Tooze, 1973; Gross, 1970). Conceptually, one of the major advances in understanding this relationship has been the demonstration that a protein related to the major envelope glycoprotein of the MuLV gp70 can be a component of normal cells, even in the absence of detectable virus (Del Villano et al., 1975; Tung et al., 1975; Kennel and Feldman, 1976). In this chapter, we review our data which led to this conclusion.