Cell envelope of Candida albicans.

In this review, the cell envelope of the human pathogenic yeast Candida albicans includes the plasma membrane and the mannoproteins, enzymes, beta-glucans, and chitin of the wall. The organization of the wall is complex and ultrastructural studies show distinct "layers". Mannoprotein is distributed throughout the wall but is concentrated on the exterior surface and adjacent to the plasma membrane. The mannoproteins contain the antigenic determinants of the yeast cells. The major structural components of the wall are beta-1,3- and beta 1,6-glucans, and these two linkages are present in almost equal amounts. Chitin is concentrated at the bud scar, but small amounts are located over the entire wall where it appears to be linked to beta-1,6-glucan. Chemical bonding both within and between wall components confers rigidity on the wall and restricts movement of molecules into and out of the cell. Soluble enzymes are retained within the wall matrix, but a number of enzymes and proteins are excreted. The plasma membrane of C. albicans is similar to that isolated from other fungi and contains the proton pump ATPase and enzymes involved in biosynthesis of the wall such as chitin synthase and beta-1,3-glucan synthase.