Expression of a variant form of actin and additional polypeptide changes following chemical-induced in vitro neoplastic transformation of human fibroblasts.
Malignant human fibroblasts, transformed in vitro by a single chemical treatment, and the untransformed parental cells have been compared by two-dimensional gel electrophoresis of their proteins. One transformed cell line, HUT-14, exhibits an abundance of a new polypeptide, A' (pI 5.2; molecular weight 44,000), amounting to approximately 3% of the cellular protein. There are at least 23 additional differences in polypeptides out of greater than 1000 electrophoretically distinguishable species. The A' polypeptide has been identified as a variant form of actin by immunoprecipitation with anti-actin antibody and comparison of its tryptic peptide patterns with those produced by beta- and gamma-actin polypeptides also found in HUT-14 cells. A' is distinguishable from the normal forms of actin (alpha, beta, and gamma polypeptides) in that it is more acidic and migrates at a slower rate in sodium dodecyl sulfate gels. Synthesis of A' may occur as a result of a somatic mutation affecting one of the normal actin genes. The electrophoretic behavior of A' in two-dimensional gels is compatible with several mutation models.
D000199:Actins / Q000096:biosynthesis*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts; D014644:Genetic Variation; D006801:Humans; D007525:Isoelectric Focusing; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D010452:Peptide Biosynthesis; D010446:Peptide Fragments / Q000032:analysis; D010649:Phenylalanine / Q000378:metabolism
D000199:Actins; D010446:Peptide Fragments; D010649:Phenylalanine; D008715:Methionine