Growth-correlated distribution of two types of plasma membrane particles of Schizosaccharomyces pombe

The particle ultrastructure at or near the growing pole and in lateral regions of the plasma membrane of exponential phase Schizosaccharomyces pombe was examined by means of the freeze-fracture technique. The uninvaginated growing pole was predominantly embedded with small globular particles of 4–8 nm in diameter with no depressions. In contrast, densely invaginated lateral regions, where no growth occurs, were rich in large cratered particles of 10–15 nm in diameter with central depressions. On cytokinesis, the middle of the cell near the division furrow became uninvaginated and was predominantly embedded with small globular particles. This is the first report directly concerning the growth-correlated distribution of yeast plasma membrane particles.