[Comparative study of the oncornavirus A and D proteins of human J-96 cells by the methods of isoelectric focusing and polyacrylamide gel electrophoresis].

Three peaks of 14C-radioactivity with buoyant densities of 1.23--1.24, 1.26 and 1.29 g/ml were detected in a cytoplasmic extract of J-96 cells upon equilibrium centrifugation in sucrose gradient. Electron microscopy of the 1.23--1.24 g/ml buoyant density fraction revealed particles 60--80 nm in diameter showing morphology characteristic of oncornavirus A. Isoelectric focusing in polyacrylamide gel showed polypeptides of extracellular D virus and oncornavirus A to differ in isofocusing points (pI). Proteins of extracellular D virus were localized in zones with pH 3.7, 4.0, 4.4, 4.7, 5.6, 6.5, 8.1, 9.45, and 10.0; polypeptide of intracytoplasmic oncornavirus A had the following isofocusing points: 4.0, 4.9, 6.7, 7.3, 9.0, 9.45 and over 10.0. Electrophoresis of polypeptides of D virus and intracellular oncornavirus A revealed differences in the molecular weights of the components. No proteins with molecular weights of 10,000, 12,000, 15,000, and 27,000 dalton characteristic of the extracellular D virus were found in oncornavirus A virions. The analysis of protein patterns obtained in parallel experiments of isoelectric focusing and polyacrylamide gel electrophoresis suggests that oncornaviruses A and D of J-96 cells differ in the characteristics (pI and molecular weight) of the structural polypeptide components.