Figure 1 .

Molecular organization of the yeast cell wall (adapted from Lesage and Bussey 2006, doi: 10.1128/MMBR.00038-05; amended with permission from American Society for Microbiology). Chains of β-1,3-glucan, branched through β-1,6-linkages, form a mesh network that provides the mechanical strength of the cell wall and also serves as a scaffold for the attachment of cell wall proteins (CWPs). Pir-CWPs are attached directly to β-1,3-glucan through a Gln residue within their internal repeats that is converted to a Glu (E) residue in the linkage. These proteins have the potential to cross-link β-1,3-glucan chains through multiple repeat sequences. GPI-CWPs are attached to the network indirectly through a linkage between the lipidless GPI remnant (GPI_r) and β-1,6-glucan. Chitin, a polymer of β-1,4-N-actetylglucosamine (GlcNAc), can be attached either directly to β-1,3-glucan on the inner surface or indirectly by β-1,6-glucan to the outer surface. The latter attachment is induced in response to cell wall stress. The nature of the linkage between β-1,3-glucan and β-1,6-glucan chains is still uncharacterized.