title: An extraction resistant tensile protein in the protoplasmic matrix of Physarum.
abstract: A thorough extraction of plasmodia of Physarum polycephalum by sequential treatment with 1% Triton x-100, 0.6 M KI, 4% SDS plus 7 M urea leaves behind an elastic cell ghost, which represents a cytoplasmic matrix protein arranged as a continuous network in all cell regions. The protein is present in the ectoplasm as well as in the endoplasm. The extraction-resistant ghosts reveal filaments 2-3 nm in diameter, perform a conspicuous volume condensation upon the addition of mM-concentrations of di- and trivalent cations and can be partially solubilized in 4.5 M guanidinium chloride plus 25% 2-mercaptoethanol at 70 degrees C. SDS-gel electrophoresis shows a distinct band at 43,000 daltons and a faint high molecular weight component suggesting a similarity to muscle connection.
mesh_terms: D003285:Contractile Proteins / Q000302:isolation & purification*; D003902:Detergents; D008854:Microscopy, Electron; D008970:Molecular Weight; D017830:Octoxynol; D010804:Physarum / Q000032:analysis* / Q000648:ultrastructure; D011092:Polyethylene Glycols; D012967:Sodium Dodecyl Sulfate; D014508:Urea
chemical_list: D003285:Contractile Proteins; D003902:Detergents; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols; D014508:Urea; D017830:Octoxynol