|Name:||solute carrier family 20 (phosphate transporter), member 1|
|PubMed (8041748):|| Kavanaugh MP, Miller DG, Zhang W, Law W, Kozak SL, Kabat D, Miller AD. Cell-surface receptors for gibbon ape leukemia virus and amphotropic murineretrovirus are inducible sodium-dependent phosphate symporters.Proc Natl Acad Sci U S A. 1994 Jul 19;91(15):7071-5. PMID: 8041748 [PubMed - indexed for MEDLINE]|
Cell surface receptors for gibbon ape leukemia virus (Glvr-1) and murine amphotropic retrovirus (Ram-1) are distinct but related proteins having multiple membrane-spanning regions. Distant homology with a putative phosphate permease of Neurospora crassa suggested that these receptors might serve transport functions. By expression in Xenopus laevis oocytes and in mammalian cells, we have identified Glvr-1 and Ram-1 as sodium-dependent phosphate symporters. Two-electrode voltage-clamp analysis indicates net cation influx, suggesting that phosphate is transported with excess sodium ions. Phosphate uptake was reduced by > 50% in mouse fibroblasts expressing amphotropic envelope glycoprotein, which binds to Ram-1, indicating that Ram-1 is a major phosphate transporter in these cells. RNA analysis shows wide but distinct tissue distributions, with Glvr-1 expression being highest in bone marrow and Ram-1 in heart. Overexpression of Ram-1 severely repressed Glvr-1 synthesis in fibroblasts, suggesting that transporter expression may be controlled by net phosphate accumulation. Accordingly, depletion of extracellular phosphate increased Ram-1 and Glvr-1 expression 3- to 5-fold. These results suggest simple methods to modulate retroviral receptor expression, with possible applications to human gene therapy.