Solubilization of complexes between tumor‐associated and H‐2 antigens from a tumor cell plasma membrane

摘要

AbstractThe tumor‐associated cell surface antigens (TAA) gp71 and AgI cocap H‐2, but are not associated with H‐2 following solubilization of membranes with detergent. We have attempted to solubilize intact TAAIH‐2 complexes from surface‐labeled L cells using decreasing concentrations of the nonionic detergent Nonidet‐P40 (NP40). Associations between gp71 and H‐2 and between AgI and H‐2 in solution were detected using sequential immunoprecipitation. gp7UH‐2 and AgI/H‐2 complexes were solubilized at the lowest detergent concentration used, 0.01% NP40. No co‐ precipitation of these antigen pairs was seen at any higher NP 40 concentration tested. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that precipitation of antigens solublized in 0.01% NP40 leads to co precipitation of a small number of other protein peaks and does not appear to involve wholesale inclusion of labeled membrane proteins. These results, together with previous observations of cocapping between TAA and H‐2 antigens, suggest that the molecules are associated with one another in the membrane. Detergent solubilization of membranes with all but the most gentle conditions leads to disrup