FIG. 2.

Velocity centrifugation analysis of M protein material released from cells coexpressing TGEV M and E genes. The culture medium from vT7-3-infected, transfected, and labeled RK13 cells was centrifuged on a 20 to 45% linear sucrose gradient. The material present in each fraction was pelleted and analyzed directly by SDS–12% PAGE and autoradiography. The position (top of the peak) of labeled TGEV virions sedimented in a parallel gradient is shown by an open triangle. The sucrose concentrations in the fractions corresponding to the sedimentation peaks of pseudoparticles and virions, respectively, are shown (arrow).