Topographical stability of lateral regions of the Schizosaccharomyces pombe plasma membrane as revealed by invagination characteristics

Abstract

The characteristics, especially the stability, of plasma-membrane invaginations in Schizosaccharomyces pombe were studied using freeze-fracture techniques. The plasma membrane of exponential-phase S. pombe was characterized by the uninvaginated growing pole(s) and by the existence of particularly long invaginations, reaching up to 5 μm, in the nongrowing lateral regions. The stationary-phase plasma membrane was characterized by densely invaginated cell poles and by the high density of invaginations. After reinoculation of stationary-phase cells in fresh media, preexisting invaginations in the cell poles disappeared when the latter became the growing pole. In lateral regions of the plasma membrane, however, deep invaginations, characteristic of the stationary phase, were well conserved. The results obtained suggest the topographical stability of nongrowing lateral regions of the S. pombe plasma membrane.