Abstract
Differences in proteins between cells grown as suspension cultures and those grown as attached cultures were studied by comparing the proteins of detergent-resistant cytoskeletons prepared from peripheral blood leukocytes and a lymphoblastoid cell line (GM607) (both grown as suspension cultures) and those of human skin fibroblasts (grown as attached cultures) by two-dimensional gel electrophoresis. The major cytoskeletal proteins of the leukocytes were also present in the protein pattern of GM607 cytoskeletons. In contrast, the fibroblast cytoskeletal protein pattern contained four groups of proteins that differed from the patterns of the leukocytes and GM607. Three groups (Cytoskf:8--10, :14--16, and :17--18) showed qualitative differences, and the fourth group (Cytoskf:11 and :13) showed quantitative differences. In addition, surface labeling of GM607 and human fibroblasts with 125I demonstrated that substantial amounts of vimentin and actin are exposed at the surface of the attached fibroblasts, but there is little evidence of similar exposure at the surface of the suspension-grown GM607. Cytoskf:11 and :13 in fibroblast preparations were also labeled with the 125I. These results demonstrate some differences in cytoskeletal protein composition between different types of cells could be related to their ability or lack of ability to grow as attached cells in tissue culture.
Cholera toxin can catalyze ADP-ribosylation of cytoskeletal proteins.
