Cell Surface Binding Proteins for the Major Envelope Glycoprotein of Murine Leukemia Virus 1

Summary

The 71,000 M_r major envelope glycoprotein (gp71) of Rauscher murine leukemia virus has been shown to bind to susceptible cells in vitro. [³H]Leucine surface polypeptides bound to ¹²⁵I-labeled gp71 were stripped from BALB/c thymocytes with nonionic detergent and chemically linked with the cleavable bifunctional reagent methyl 4-mercaptobutyrimidate. Soluble disulfide-linked ¹²⁵I-labeled gp71 bound thymocyte surface polypeptide oligomers were precipitated with adsorbed gp71 antisera and after reductive cleavage, molecular weights (SDS-PAGE) of approximately 23,000, 32,000, 45,000, 65,000, 90,000, and 170,000 M _r were seen. Experiments demonstrating the cross-linked-dependent immunoprecipitation of ¹²⁵I-labeled gp71 - thymocyte surface polypeptide oligomers with antiserum having reactivity to products of the major histocompatibility locus (H-2^d and la) and also for the gag gene products (p30 and p15) are described. The involvement of these thymocyte surface polypeptides in structuring the functional receptor for ecotropic oncornaviruses is discussed.