期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1980
卷号：77
期号：8
页码：4988-4992
DOI：10.1073/pnas.77.8.4988
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A protein that avidly binds gp70, the envelope antigen of Rauscher murine leukemia virus (RMuLV), has been purified from the culture medium used for growth of BALB/c 3T3 mouse cells. Gel filtration chromatrography revealed the apparent Mr 10,000 BPgp70 was efficiently labeled when BALB/c 3T3 cells were grown in medium containing [3H]leucine, indicating a cellular origin for BPpg70. Metabolically labeled [3H]BPgp70 was not immunoprecipitated by IgG-anti RMuLV-gp&) alone, but was immunoprecipitated when gp70 was added, an indicaton of BPgp70 x gp70 complex formation. The dissociation constant estimated by immunoprecitipation agreed with the apparent Kd for binding of gp70 to BALB/c 3T3 cells. BPgp70 reversibly inhibited specific binding of 125I-labeled BMuLV-gp70 to BALB/c 3T3 cells when it was incubated with the 125I-labeled gp70 first. These data yielded a dissociation constant similar to that calculated from the immunoprecipitation data. 125I-Labeled BPgp70 also bound specifically to cells infected with RMuLV, but not to uninfected cells. Incubation of BALB/c 3T3 cells with the IgG fraction of an antiserum to BPgp70 inhibited the specific binding of 125I-labeled gp70 to these cells, but preimmune IgG did not. Complete inhibition was achieved at a less than 100:1 ratio of IgG anti-BPgp70 to gp70 binding sites.
