Radioimmunoprecipitation Analysis Research Articles

Normal chicken cells (chf −) express a surface antigen which cross-reacts with determinants of the major envelope glycoprotein (gp85) of avian myeloblastosis virus

Using rabbit antisera raised against the purified major envelope glycoprotein (gp85) of avian myeloblastosis virus (AMV), we were unable to differentiate between normal chicken cells carrying the chicken-helper factor (chf +) from those lacking this endogenous virus information (chf −) in several serological assays, including competition radioimmunoassay and membrane immunofluorescence. Radioimmunoprecipitation analysis of the material recognized in uninfected chf(+) and chf(-) chicken cells by the rabbit anti-AMV gp85 antisera revealed the presence in immune precipitates of both cell types of a high molecular weight glycoprotein (∼125,000), while low amounts of gp85 were precipitated only from the chf(+) cells. In contrast, antisera raised against the gp85s of three other avian oncornaviruses did not recognize the 125,000-dalton molecule in either cell type, although gp85 was again precipitated from the chf(+) chicken cells. The high molecular weight glycoprotein (denoted NCG) appears to represent a normal chicken cell surface glycoprotein which is antigenically cross-reactive with unique determinants of AMV gp85, presumably dependent on the carbohydrate portion of the molecules. The significance of this cross-reactivity is discussed, as well as the interpretation of previous results obtained through the use of these rabbit anti-AMV gp85 antisera.

Virus-specific precursor polypeptides in cells infected with Rauscher leukemia virus: Synthesis, identification, and processing

The synthesis of virus-specific polypeptides in JLS-V9 and JLS-V5 cells infected with Rauscher leukemia virus (R-MuLV) was studied in pulse-chase experiments, followed by radioimmunoprecipitation analysis with polyvalent and monospecific antisera against R-MuLV proteins. Two glycosylated polypeptides with molecular weights of about 8 ( env-pr82) were identified as precursors of the virion envelope polypeptides gp69/71 and p15(E). On the other hand, virion polypeptides p30 and pl5 are derived from a 75,000-( gag-pr75) and a 65,000-dalton ( gag-pr65) precursor polypeptide. These precursor-product relations were confirmed by analysis of chymotryptic digests of virion polypeptides and their precursors. In the presence of the arginine analog canavanine two polypeptides with molecular weights of 82,000 and 72,000 ( gag-pr82 and gag-pr72, respectively) were synthesized instead of gag-pr75 and gag-pr65. Processing of precursor polypeptides is reduced in the presence of canavanine. From these results, we conclude that gag-pr82 is possibly the primary gag-gene product and is cleaved into gag-pr75. These studies provided the following additional information: First, we established that immediately after cleavage of their precursors, gp69/71 is found on the outer surface of the cell and p30, p15, and p12 leave the cell as components of budding virions. Therefore, these polypeptides were detected intracellularly in very small amounts only. Polypeptide p15(E) was present within the cell as well as on its outer surface. Second, despite a great similarity in virus-specific (precursor) polypeptides detected in JLS-V9 and JLS-V5 cells, small differences in molecular weights of some of these polypeptides were observed after SDS-PAGE.

A comparative immunologic and electrophoretic analysis of rat and mouse caseins

1. 1. Caseins from rat and mouse milk were purified following rennin-Ca 2= precipitation. 2. 2. Acrylamide gel electrophoresis revealed four components in rat and five componenst in mouse casein. At least one component migrated similarly in both caseins. 3. 3. Immunodiffusion and immunoelectrophoretic analysis indicated that anti-bodies to mouse casein exhibit incomplete cross-reactivity to similar casein components in mouse and rat milk. Antibodies to rat casein recognized four components in rat milk, an donly one component in mouse milk. The mouse milk component was identical to one of rat components. 4. 4. Radioimmunoprecipitation analysis suggested that antibodies against rat and mouse casein recognize heterologous caseins, but precipitation in less efficient.