THE CELLULAR RECEPTOR FOR GIBBON APE LEUKEMIA-VIRUS IS A NOVEL HIGH-AFFINITY SODIUM-DEPENDENT PHOSPHATE TRANSPORTER

The primate type C retrovirus gibbon ape leukemia virus (GaLV) has bee n shown to use a widely expressed, multiple membrane-spanning protein of unknown function as its cell surface receptor on human cells (GLVR1 ) (Johann, S. V., Gibbons, J. J., and O'Hara, B. (1999) J. Virol. 66, 1635-1640; O'Hara, B., Johann, S. V., Klinger, H. P., Blair, D. G., Ru binson, H., Dunni, K. J., Sass, P., Vitek, S. M., and Robins, T. (1990 ) Cell Growth Diff. 1, 119-127). Here we present evidence that the rec eptor for GaLV (GLVR1) functions as a sodium dependent transporter of inorganic phosphate. GLVR1 is shown to have approximately 3-4-fold hig her affinity for phosphate than other mammalian phosphate transporters described to date. Productive infection of GLVR1-expressing cells by GaLV, but not other retroviruses, results in the complete blockade of GLVR1-specific uptake of inorganic phosphate. Since productive infecti on of cells with GaLV is generally not cytotoxic, it is likely that mo re than one phosphate transporter exists on the cell surface. Our data suggest that GLVR1 represents a sodium-dependent phosphate transporte r that differs from other mammalian phosphate transporters in structur e, affinity for phosphate, and function.