Ghosh A K, Bachmann M H, Hoover E A, Mullins J I
Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305-5402.
J Virol. 1992 Jun;66(6):3707-14. doi: 10.1128/JVI.66.6.3707-3714.1992.
Retrovirus infection is initiated by the binding of virus envelope glycoprotein to a receptor molecule present on cell membranes. To characterize a receptor for feline leukemia virus (FeLV), we extensively purified the viral envelope glycoprotein, gp70, from culture supernatants of FeLV-61E (subgroup A)-infected cells by immunoaffinity chromatography. Binding of purified 125I-labeled gp70 to the feline T-cell line 3201 was specific and saturable, and Scatchard analysis revealed a single class of receptor binding sites with an average number of 1.6 x 10(5) receptors per cell and an apparent affinity constant (Ka) of 1.15 x 10(9) M-1. Cross-linking experiments identified a putative gp70-receptor complex of 135 to 140 kDa. Similarly, coprecipitation of 125I-labeled cell surface proteins with purified gp70 and a neutralizing but noninterfering anti-gp70 monoclonal antibody revealed a single cell surface protein of approximately 70 kDa. These results indicate that FeLV-A binds to feline T cells via a 70-kDa cell surface protein, its presumptive receptor.
逆转录病毒感染是由病毒包膜糖蛋白与细胞膜上存在的受体分子结合引发的。为了鉴定猫白血病病毒（FeLV）的受体，我们通过免疫亲和层析从感染FeLV-61E（A亚群）的细胞培养上清液中广泛纯化了病毒包膜糖蛋白gp70。纯化的125I标记的gp70与猫T细胞系3201的结合具有特异性且可饱和，Scatchard分析显示存在一类单一的受体结合位点，每个细胞平均有1.6×10^5个受体，表观亲和常数（Ka）为1.15×10^9 M^-1。交联实验鉴定出一种推定的135至140 kDa的gp70-受体复合物。同样，用纯化的gp70和一种中和但不干扰的抗gp70单克隆抗体对125I标记的细胞表面蛋白进行共沉淀，结果显示有一种约70 kDa的单一细胞表面蛋白。这些结果表明，FeLV-A通过一种70 kDa的细胞表面蛋白（其推定受体）与猫T细胞结合。
