title: Association of three chicken proteins with the 34 kD target of Rous sarcoma virus tyrosine kinase.
abstract: Transformation of chicken embryo fibroblasts by avian retroviruses induces the tyrosine phosphorylation of a 34-39 kD cellular protein (p34). In vitro, p34 isolated from intestine interacts with F-actin in a Ca2+-dependent manner. We report here that, in the absence of Ca2+ chelators, three proteins co-purified with p34 extracted from a cytosolic or membrane fraction of chicken embryo fibroblasts; these two fractions account respectively for 10-20% and 50% of the total cellular p34. Isolated from the cytosoluble fraction of fibroblasts by sucrose gradient centrifugation and hydrophobic chromatography, p34 and the other proteins behaved as a homogeneous species upon non-denaturing gel electrophoresis, gel filtration, and CsCl density gradient centrifugation, thus indicating a strong association. Moreover, an analysis by electron microscopy following uranyl acetate staining revealed particles with a raspberry-like shape. This association was always disrupted by the calcium-chelating agent, EGTA.
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000201:enzymology*; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002642:Chick Embryo; D005347:Fibroblasts / Q000378:metabolism; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D014357:Trypsin
chemical_list: D010446:Peptide Fragments; D011506:Proteins; D011505:Protein-Tyrosine Kinases; D014357:Trypsin