Dissimilar modes of expression of beta- and gamma-actin in normal and leukemic human T lymphocytes.

Actin polypeptides are the most abundant protein components of replicating normal human T lymphocytes, comprising 16% of the total cellular protein. Unlike other replicating cell types which synthesize equal proportions of beta- and gamma-actin polypeptides, T cells synthesize beta-actin as the predominant species. By contrast, leukemic T cells (the Molt-4 cell line) synthesize nearly equal proportions of beta- and gamma-actin. In addition, novel forms of beta-actin in normal T cells and of beta- and gamma-actin in Molt-4 cells appear to be present, perhaps resulting from a post-translational modification process. Otherwise, both divergent T cell types express a relatively common spectrum of polypeptide species, thereby suggesting that regulation of actin biosynthesis may be involved in the neoplastic transformation process.