Investigations of plasma membrane particles in Saccharomyces cerevisiae protoplasts are shortly reviewed. Particle arrangement into a hexagonal patterns is considered to reflect some minute changes in the biomembrane organization rather than functional differentiation. Plasma membrane invaginations are proved to be rigid structures capable of migrating in the fluid domain of the membrane. Density of the particles per unit area is related to the degree of membrane stretching which suggest that upon membrane extension new protein molecules are shifted towards the hydrophobic layer of the membrane.