A quantitative difference in the movement of marker particles in the plasma membrane of 3T3 mouse fibroblasts and their polyoma transformants

The movement of particles in the plasma membrane of 3T3 mouse fibroblasts and their polyoma and SV40 transformants was quantitatively investigated by measuring at regular time intervals the perimeter and area of a triangle formed by three marker particles on the dorsal membrane [1]. 3T3, polyoma (Py) and SV40 transformed 3T3 cells distinctly showed both an irregular slow movement occupying 60% of the time between cell divisions and an irregular fast movement phase. The two phases alternated at irregular time intervals and differed in rate by a factor of 12. The movement of particles on Py3T3 and SV3T3 cell membranes was 6 times slower in both phases and showed a lower index of systematic particle movement than 3T3 cells.